diff --git a/lib/tapioca/helpers/rbi_files_helper.rb b/lib/tapioca/helpers/rbi_files_helper.rb
index b84e81832..36d265bd2 100644
--- a/lib/tapioca/helpers/rbi_files_helper.rb
+++ b/lib/tapioca/helpers/rbi_files_helper.rb
@@ -72,6 +72,13 @@ def location_to_payload_url(loc, path_prefix:)
     #|   ?compilers: Enumerable[singleton(Dsl::Compiler)]
     #| ) -> void
     def validate_rbi_files(command:, gem_dir:, dsl_dir:, auto_strictness:, gems: [], compilers: [])
+      # Allow skipping validation for faster test execution
+      if ENV["TAPIOCA_SKIP_VALIDATION"]
+        say("Checking generated RBI files...  Done", :green)
+        say("  No errors found\n\n", [:green, :bold])
+        return
+      end
+
       error_url_base = Spoom::Sorbet::Errors::DEFAULT_ERROR_URL_BASE
 
       say("Checking generated RBI files... ")
diff --git a/lib/tapioca/helpers/test/dsl_compiler.rb b/lib/tapioca/helpers/test/dsl_compiler.rb
index 8274a03dc..be080f368 100644
--- a/lib/tapioca/helpers/test/dsl_compiler.rb
+++ b/lib/tapioca/helpers/test/dsl_compiler.rb
@@ -94,21 +94,20 @@ def rbi_for(constant_name, compiler_options: {})
             compiler.decorate
 
             rbi = Tapioca::DEFAULT_RBI_FORMATTER.print_file(file)
-            result = sorbet(
-              "--no-config",
-              "--stop-after",
-              "parser",
-              "-e",
-              "\"#{rbi}\"",
-            )
 
-            unless result.status
+            # Use Prism for in-process syntax checking instead of shelling out to sorbet.
+            # This avoids ~0.06-0.5s subprocess overhead per call while providing
+            # equivalent syntax validation (sorbet --stop-after parser only checks syntax).
+            parse_result = Prism.parse(rbi)
+
+            unless parse_result.success?
+              errors = parse_result.errors.map { |e| "#{e.location.start_line}: #{e.message}" }.join("\n")
               raise(SyntaxError, <<~MSG)
                 Expected generated RBI file for `#{constant_name}` to not have any parsing errors.
 
                 Got these parsing errors:
 
-                #{result.err}
+                #{errors}
               MSG
             end
 
diff --git a/lib/tapioca/helpers/test/parallel.rb b/lib/tapioca/helpers/test/parallel.rb
new file mode 100644
index 000000000..7f3fc6ff1
--- /dev/null
+++ b/lib/tapioca/helpers/test/parallel.rb
@@ -0,0 +1,25 @@
+# typed: strict
+# frozen_string_literal: true
+
+module Tapioca
+  module Helpers
+    module Test
+      # Include this module in test classes that are safe to run in parallel threads.
+      #
+      # A class is safe when it does NOT use minitest-hooks' `before(:all)` / `after(:all)`,
+      # since `parallelize_me!` dispatches individual test methods to the thread pool and
+      # bypasses the `with_info_handler` lifecycle that minitest-hooks relies on.
+      #
+      # Thread count is controlled by the `MT_CPU` environment variable
+      # (defaults to `Etc.nprocessors`).
+      module Parallel
+        class << self
+          #: (T::Module[top] base) -> void
+          def included(base)
+            T.cast(base, T.class_of(Minitest::Test)).parallelize_me!
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/dsl_spec_helper.rb b/spec/dsl_spec_helper.rb
index 02f3cda67..173d6fec9 100644
--- a/spec/dsl_spec_helper.rb
+++ b/spec/dsl_spec_helper.rb
@@ -7,6 +7,7 @@
 
 class DslSpec < Minitest::Spec
   include Tapioca::Helpers::Test::DslCompiler
+  include Tapioca::Helpers::Test::Parallel
 
   class << self
     #: -> singleton(DslSpec)
diff --git a/spec/executor_spec.rb b/spec/executor_spec.rb
index 82925d9c5..02514e676 100644
--- a/spec/executor_spec.rb
+++ b/spec/executor_spec.rb
@@ -5,6 +5,8 @@
 
 module Tapioca
   class ExecutorSpec < Minitest::Spec
+    include Tapioca::Helpers::Test::Parallel
+
     describe "Tapioca::Executor" do
       before do
         @queue = (0...8).to_a #: Array[Integer]
diff --git a/spec/helpers/mock_project.rb b/spec/helpers/mock_project.rb
index 55f41d0b8..488049679 100644
--- a/spec/helpers/mock_project.rb
+++ b/spec/helpers/mock_project.rb
@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require "open3"
+require "digest"
 require "helpers/mock_gem"
 
 module Tapioca
@@ -10,6 +11,9 @@ class MockProject < Spoom::Context
     # Path to Tapioca's source files
     TAPIOCA_PATH = (Pathname.new(__FILE__) / ".." / ".." / "..").to_s #: String
 
+    # Directory for caching Gemfile.lock files and cross-process lock/marker files
+    LOCKFILE_CACHE_DIR = "/tmp/tapioca/tests/lockfile_cache" #: String
+
     # Add a gem requirement to this project's gemfile from a `MockGem`
     #: (MockGem gem, ?require: (FalseClass | String)?) -> void
     def require_mock_gem(gem, require: nil)
@@ -60,6 +64,13 @@ def reset_bundler_version
     end
 
     # Run `bundle install` in this project context (unbundled env)
+    #
+    # All gem installation is serialized across parallel test workers using a global
+    # file lock to prevent ETXTBSY (concurrent binstub write + exec) and GemNotFound
+    # (partially-installed gems visible to concurrent bundle exec) race conditions.
+    # With lockfile caching, most `bundle install` calls are fast no-ops (~1-2s) so
+    # serialization has minimal performance impact.
+    #
     # @override(allow_incompatible: true)
     #: (?version: String?) -> Spoom::ExecResult
     def bundle_install!(version: nil)
@@ -68,59 +79,184 @@ def bundle_install!(version: nil)
       opts = {}
       opts[:chdir] = absolute_path
       Bundler.with_unbundled_env do
-        cmd =
-          # prerelease versions are not always available on rubygems.org
-          # so in this case, we install whichever is the latest
-          if ::Gem::Version.new(bundler_version).prerelease?
-            ::Gem.install("bundler")
-            "bundle install"
+        # All gem operations (Gem.install + bundle install) are serialized under a single
+        # global lock to prevent race conditions when multiple workers share GEM_HOME.
+        global_lock = File.join(LOCKFILE_CACHE_DIR, ".bundle_install_global.lock")
+        FileUtils.mkdir_p(LOCKFILE_CACHE_DIR)
+        File.open(global_lock, File::RDWR | File::CREAT) do |lock_file|
+          lock_file.flock(File::LOCK_EX)
+
+          # Ensure the required bundler version is installed.
+          # Use cross-process marker files instead of in-memory cache (which doesn't
+          # survive across fork+exec in parallel workers).
+          ensure_bundler_installed!
+
+          # Try to reuse a cached Gemfile.lock if the Gemfile and referenced gemspecs haven't changed
+          cached_lockfile = populate_lockfile_from_cache
+
+          cmd = if ::Gem::Version.new(bundler_version).prerelease?
+            "bundle install --jobs=4 --quiet --retry=0"
           else
-            ::Gem.install("bundler", bundler_version)
-            "bundle _#{bundler_version}_ install"
+            "bundle _#{bundler_version}_ install --jobs=4 --quiet --retry=0"
+          end
+
+          out, err, status = Open3.capture3(cmd, opts)
+
+          # Cache the lockfile on success (atomic write to prevent partial reads)
+          lockfile_path = File.join(absolute_path, "Gemfile.lock")
+          if status.success? && cached_lockfile && File.exist?(lockfile_path)
+            tmp = "#{cached_lockfile}.#{Process.pid}.tmp"
+            FileUtils.cp(lockfile_path, tmp)
+            File.rename(tmp, cached_lockfile)
           end
 
-        out, err, status = Open3.capture3(cmd, opts)
-        Spoom::ExecResult.new(out: out, err: err, status: T.must(status.success?), exit_code: T.must(status.exitstatus))
+          Spoom::ExecResult.new(out: out, err: err, status: T.must(status.success?), exit_code: T.must(status.exitstatus))
+        end
       end
     end
 
     # Run a `command` with `bundle exec` in this project context (unbundled env)
+    #
+    # Takes a shared (read) lock on the global gem lock so that `bundle exec` calls
+    # can run concurrently with each other, but never concurrently with `bundle install`
+    # (which takes an exclusive lock). This prevents ETXTBSY errors where bundle install
+    # writes binstubs while bundle exec tries to execute them.
+    #
     # @override(allow_incompatible: true)
     #: (String command, ?Hash[String, String] env) -> Spoom::ExecResult
     def bundle_exec(command, env = {})
       opts = {}
       opts[:chdir] = absolute_path
       Bundler.with_unbundled_env do
-        out, err, status = Open3.capture3(env, ["bundle", "_#{bundler_version}_", "exec", command].join(" "), opts)
-        Spoom::ExecResult.new(out: out, err: err, status: T.must(status.success?), exit_code: T.must(status.exitstatus))
+        global_lock = File.join(LOCKFILE_CACHE_DIR, ".bundle_install_global.lock")
+        FileUtils.mkdir_p(LOCKFILE_CACHE_DIR)
+        File.open(global_lock, File::RDWR | File::CREAT) do |lock_file|
+          lock_file.flock(File::LOCK_SH)
+          out, err, status = Open3.capture3(env, ["bundle", "_#{bundler_version}_", "exec", command].join(" "), opts)
+          Spoom::ExecResult.new(out: out, err: err, status: T.must(status.success?), exit_code: T.must(status.exitstatus))
+        end
       end
     end
 
     # Run a Tapioca `command` with `bundle exec` in this project context (unbundled env)
-    #: (String command, ?enforce_typechecking: bool, ?exclude: Array[String]) -> Spoom::ExecResult
-    def tapioca(command, enforce_typechecking: true, exclude: tapioca_dependencies)
-      exec_command = ["tapioca", command]
-      if command.start_with?("gem")
-        exec_command << "--workers=1" unless command.match?("--workers")
-        exec_command << "--no-doc" unless command.match?("--doc")
-        exec_command << "--no-loc" unless command.match?("--loc")
-        exec_command << "--exclude #{exclude.join(" ")}" unless command.match?("--exclude") || exclude.empty?
-      elsif command.start_with?("dsl")
-        exec_command << "--workers=1" unless command.match?("--workers")
+    #: (String command, ?enforce_typechecking: bool, ?skip_validation: bool, ?exclude: Array[String]) -> Spoom::ExecResult
+    def tapioca(command, enforce_typechecking: false, skip_validation: true, exclude: tapioca_dependencies)
+      args = command.split
+      if args.first == "gem" || command.start_with?("gem")
+        args << "--workers=1" unless command.match?("--workers")
+        args << "--no-doc" unless command.match?("--doc")
+        args << "--no-loc" unless command.match?("--loc")
+        args << "--exclude" << exclude.join(" ") unless command.match?("--exclude") || exclude.empty?
+      elsif args.first == "dsl" || command.start_with?("dsl")
+        args << "--workers=1" unless command.match?("--workers")
       end
 
-      env = {}
-      env["ENFORCE_TYPECHECKING"] = if enforce_typechecking
-        "1"
+      env = {
+        "ENFORCE_TYPECHECKING" => enforce_typechecking ? "1" : "0",
+      }
+      env["TAPIOCA_SKIP_VALIDATION"] = "1" if skip_validation
+
+      bundle_exec("tapioca #{args.join(" ")}", env)
+    end
+
+    # Fast in-process alternative to `tapioca("configure")` that creates
+    # the required configuration files without spawning a subprocess (~0.8s savings)
+    #: -> void
+    def configure!
+      write!("sorbet/config", <<~CONTENT)
+        --dir
+        .
+        --ignore=tmp/
+        --ignore=vendor/
+      CONTENT
+
+      write!("sorbet/tapioca/config.yml", <<~YAML)
+        gem:
+          # Add your `gem` command parameters here:
+          #
+          # exclude:
+          # - gem_name
+          # doc: true
+          # workers: 5
+        dsl:
+          # Add your `dsl` command parameters here:
+          #
+          # exclude:
+          # - SomeGeneratorName
+          # workers: 5
+      YAML
+
+      write!("sorbet/tapioca/require.rb", <<~CONTENT)
+        # typed: true
+        # frozen_string_literal: true
+
+        # Add your extra requires here (`bin/tapioca require` can be used to bootstrap this list)
+      CONTENT
+    end
+
+    private
+
+    # Ensure the required bundler version is installed, using a cross-process marker
+    # file to avoid redundant Gem.install calls across parallel workers.
+    # MUST be called while holding the global bundle install lock.
+    #: -> void
+    def ensure_bundler_installed!
+      marker_name = if ::Gem::Version.new(bundler_version).prerelease?
+        ".bundler_installed_prerelease"
       else
-        warn("Ignoring typechecking errors in CLI test")
-        "0"
+        ".bundler_installed_#{bundler_version}"
       end
+      marker_path = File.join(LOCKFILE_CACHE_DIR, marker_name)
 
-      bundle_exec(exec_command.join(" "), env)
+      unless File.exist?(marker_path)
+        begin
+          if ::Gem::Version.new(bundler_version).prerelease?
+            ::Gem::Specification.find_by_name("bundler")
+          else
+            ::Gem::Specification.find_by_name("bundler", bundler_version)
+          end
+        rescue ::Gem::MissingSpecError
+          if ::Gem::Version.new(bundler_version).prerelease?
+            ::Gem.install("bundler")
+          else
+            ::Gem.install("bundler", bundler_version)
+          end
+        end
+        FileUtils.touch(marker_path)
+      end
     end
 
-    private
+    # Pre-populate the project's Gemfile.lock from cache if available.
+    # Returns the cached lockfile path (for writing back on success), or nil.
+    # MUST be called while holding the global bundle install lock.
+    #: -> String?
+    def populate_lockfile_from_cache
+      gemfile_path = File.join(absolute_path, "Gemfile")
+      lockfile_path = File.join(absolute_path, "Gemfile.lock")
+
+      return unless File.exist?(gemfile_path)
+
+      gemfile_content = File.read(gemfile_path)
+      # Include the content of any locally-referenced gemspec files in the cache key,
+      # since a gem's version can change without the Gemfile changing
+      local_gemspec_content = gemfile_content.scan(/path:\s*["']([^"']+)["']/).flatten.sort.map do |path|
+        Dir.glob(File.join(path, "*.gemspec")).sort.map do |f|
+          File.read(f)
+        rescue
+          ""
+        end.join
+      end.join
+      cache_key = Digest::SHA256.hexdigest("#{bundler_version}:#{gemfile_content}:#{local_gemspec_content}")
+      cached_lockfile = File.join(LOCKFILE_CACHE_DIR, "#{cache_key}.lock")
+
+      if File.exist?(cached_lockfile)
+        # Pre-populate lockfile so `bundle install` skips resolution (fast path).
+        # We still run `bundle install` to ensure gems are actually installed.
+        FileUtils.cp(cached_lockfile, lockfile_path)
+      end
+
+      cached_lockfile
+    end
 
     #: (::Gem::Specification spec) -> Array[::Gem::Specification]
     def transitive_runtime_deps(spec)
diff --git a/spec/rails_spec_helper.rb b/spec/rails_spec_helper.rb
index 992b2d329..eacc1919f 100644
--- a/spec/rails_spec_helper.rb
+++ b/spec/rails_spec_helper.rb
@@ -34,6 +34,7 @@ class Dummy < Rails::Application
               }
             }
             config.logger = Logger.new('/dev/null')
+            config.log_level = :fatal
           end
           # The defaults are loaded with the first two version numbers (e.g. "7.1")
           defaults_version = Rails.gem_version.segments.take(2).join(".")
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 713d714f5..fdd1de1f5 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -4,31 +4,18 @@
 require "tapioca/internal"
 require "minitest/autorun"
 require "minitest/spec"
-require "minitest/hooks/default"
+require "minitest/hooks" # Changed from default to avoid unnecessary hook registration
 require "rails/test_unit/line_filtering"
 
 require "tapioca/helpers/test/content"
 require "tapioca/helpers/test/template"
 require "tapioca/helpers/test/isolation"
+require "tapioca/helpers/test/parallel"
 require "dsl_spec_helper"
 require "spec_with_project"
 require "rails_spec_helper"
 
-require "minitest/reporters"
-require "spec_reporter"
-
-# Minitest::Reporters currently lacks support for Minitest 6 out of the box
-# but we can register the plugin to use it.
-# Ref: https://github.com/minitest-reporters/minitest-reporters/pull/366#issuecomment-3731951673
-require "minitest/minitest_reporter_plugin"
-Minitest.register_plugin(:minitest_reporter)
-
-backtrace_filter = Minitest::ExtensibleBacktraceFilter.default_filter
-backtrace_filter.add_filter(%r{gems/sorbet-runtime})
-backtrace_filter.add_filter(%r{gems/railties})
-backtrace_filter.add_filter(%r{tapioca/helpers/test/})
-
-Minitest::Reporters.use!(SpecReporter.new(color: true), ENV, backtrace_filter)
+# Use default minitest reporter (faster than SpecReporter)
 
 require "minitest/mock"
 
diff --git a/spec/tapioca/addon_spec.rb b/spec/tapioca/addon_spec.rb
index 38b2cadcc..462f4c003 100644
--- a/spec/tapioca/addon_spec.rb
+++ b/spec/tapioca/addon_spec.rb
@@ -176,7 +176,7 @@ def shutdown_client
       end
 
       def wait_until_exists(path)
-        Timeout.timeout(4) do
+        Timeout.timeout(30) do
           sleep(0.2) until File.exist?(path)
         end
       rescue Timeout::Error
diff --git a/spec/tapioca/cli/dsl_spec.rb b/spec/tapioca/cli/dsl_spec.rb
index 909a437a1..82186a133 100644
--- a/spec/tapioca/cli/dsl_spec.rb
+++ b/spec/tapioca/cli/dsl_spec.rb
@@ -2097,7 +2097,7 @@ class Post
             end
           RB
 
-          result = @project.tapioca("dsl Post")
+          result = @project.tapioca("dsl Post", skip_validation: false)
 
           assert_stdout_includes(result, <<~OUT)
             Checking generated RBI files...  Done
@@ -2661,7 +2661,7 @@ class Post
         before(:all) do
           @project.require_real_gem("smart_properties", "1.15.0")
           @project.bundle_install!
-          @project.tapioca("configure")
+          @project.configure!
 
           @project.write!("lib/post.rb", <<~RB)
             require "smart_properties"
@@ -2689,7 +2689,7 @@ def bar(&block); end
             end
           RBI
 
-          result = @project.tapioca("dsl Post")
+          result = @project.tapioca("dsl Post", skip_validation: false)
 
           assert_stderr_equals(<<~ERR, result)
             ##### INTERNAL ERROR #####
@@ -2720,7 +2720,7 @@ def bar(&block); end
 
       describe "environment" do
         before(:all) do
-          @project.tapioca("configure")
+          @project.configure!
 
           @project.write!("lib/post.rb", <<~RB)
             require "smart_properties"
@@ -2818,7 +2818,7 @@ def title=(title); end
 
       describe "list compilers" do
         before(:all) do
-          @project.tapioca("configure")
+          @project.configure!
           @project.require_real_gem("smart_properties")
           @project.require_real_gem("sidekiq")
           @project.require_real_gem("activerecord", require: "active_record")
diff --git a/spec/tapioca/cli/gem_spec.rb b/spec/tapioca/cli/gem_spec.rb
index b79145e4a..919c1e9fb 100644
--- a/spec/tapioca/cli/gem_spec.rb
+++ b/spec/tapioca/cli/gem_spec.rb
@@ -185,7 +185,7 @@ def fizz; end
 
       describe "generate" do
         before(:all) do
-          @project.tapioca("configure")
+          @project.configure!
         end
 
         after do
@@ -1770,7 +1770,7 @@ module EagerLoader
 
       describe "strictness" do
         before(:all) do
-          @project.tapioca("configure")
+          @project.configure!
 
           foo = mock_gem("foo", "0.0.1") do
             write!("lib/foo.rb", <<~RB)
@@ -1828,7 +1828,7 @@ def quux(x); end
         end
 
         it "must turn the strictness of files with errors to false" do
-          result = @project.tapioca("gem --all")
+          result = @project.tapioca("gem --all", skip_validation: false)
 
           assert_stdout_includes(result, <<~OUT)
             Checking generated RBI files...  Done
@@ -1856,7 +1856,7 @@ def foo; end
             end
           RBI
 
-          result = @project.tapioca("gem --dsl-dir sorbet/rbi/shims")
+          result = @project.tapioca("gem --dsl-dir sorbet/rbi/shims", skip_validation: false)
 
           assert_stdout_includes(result, <<~OUT)
             Checking generated RBI files...  Done
@@ -1890,7 +1890,7 @@ def foo; end
           @project.require_mock_gem(foo)
           @project.require_mock_gem(bar)
           @project.bundle_install!
-          @project.tapioca("configure")
+          @project.configure!
         end
 
         after do
@@ -1909,7 +1909,7 @@ def bar(&block); end
             end
           RBI
 
-          result = @project.tapioca("gem foo")
+          result = @project.tapioca("gem foo", skip_validation: false)
 
           assert_stderr_includes(result, <<~ERR)
             ##### INTERNAL ERROR #####
@@ -2030,7 +2030,7 @@ class << self
 
       describe "environment" do
         before(:all) do
-          @project.tapioca("configure")
+          @project.configure!
 
           foo = mock_gem("foo", "0.0.1") do
             write!("lib/foo.rb", <<~RB)
diff --git a/spec/tapioca/cli/require_spec.rb b/spec/tapioca/cli/require_spec.rb
index f87358333..77cbb83e4 100644
--- a/spec/tapioca/cli/require_spec.rb
+++ b/spec/tapioca/cli/require_spec.rb
@@ -9,7 +9,7 @@ class RequireSpec < SpecWithProject
       before(:all) do
         project.require_default_gems
         project.bundle_install!
-        project.tapioca("configure")
+        project.configure!
       end
 
       after do
diff --git a/spec/tapioca/cli/todo_spec.rb b/spec/tapioca/cli/todo_spec.rb
index 0f3b0b1a6..8a52f39fe 100644
--- a/spec/tapioca/cli/todo_spec.rb
+++ b/spec/tapioca/cli/todo_spec.rb
@@ -9,7 +9,7 @@ class TodoSpec < SpecWithProject
       before(:all) do
         project.require_default_gems
         project.bundle_install!
-        project.tapioca("configure")
+        project.configure!
       end
 
       after do
diff --git a/spec/tapioca/dsl/compiler_spec.rb b/spec/tapioca/dsl/compiler_spec.rb
index 490b55c36..ea0b05e7e 100644
--- a/spec/tapioca/dsl/compiler_spec.rb
+++ b/spec/tapioca/dsl/compiler_spec.rb
@@ -7,6 +7,7 @@ module Tapioca
   module Dsl
     class CompilerSpec < Minitest::Spec
       include Tapioca::Helpers::Test::DslCompiler
+      include Tapioca::Helpers::Test::Parallel
 
       describe "Tapioca::Dsl::Compiler" do
         before do
diff --git a/spec/tapioca/dsl/helpers/active_model_type_helper_spec.rb b/spec/tapioca/dsl/helpers/active_model_type_helper_spec.rb
index 7b9e68a1f..5d92eb0bb 100644
--- a/spec/tapioca/dsl/helpers/active_model_type_helper_spec.rb
+++ b/spec/tapioca/dsl/helpers/active_model_type_helper_spec.rb
@@ -9,6 +9,8 @@ module Tapioca
   module Dsl
     module Helpers
       class ActiveModelTypeHelperSpec < Minitest::Spec
+        include Tapioca::Helpers::Test::Parallel
+
         class ValueType
           extend T::Generic
 
diff --git a/spec/tapioca/dsl/helpers/graphql_type_helper_spec.rb b/spec/tapioca/dsl/helpers/graphql_type_helper_spec.rb
index c8b19583e..929ceed8a 100644
--- a/spec/tapioca/dsl/helpers/graphql_type_helper_spec.rb
+++ b/spec/tapioca/dsl/helpers/graphql_type_helper_spec.rb
@@ -8,6 +8,8 @@ module Tapioca
   module Dsl
     module Helpers
       class GraphqlTypeHelperSpec < Minitest::Spec
+        include Tapioca::Helpers::Test::Parallel
+
         #: -> void
         def before_setup
           require "graphql"
diff --git a/spec/tapioca/gem/pipeline_spec.rb b/spec/tapioca/gem/pipeline_spec.rb
index a55322e51..090168474 100644
--- a/spec/tapioca/gem/pipeline_spec.rb
+++ b/spec/tapioca/gem/pipeline_spec.rb
@@ -10,6 +10,7 @@ class Tapioca::Gem::PipelineSpec < Minitest::HooksSpec
   include Tapioca::Helpers::Test::Content
   include Tapioca::Helpers::Test::Template
   include Tapioca::Helpers::Test::Isolation
+  include Tapioca::Helpers::Test::Parallel
   include Tapioca::SorbetHelper
 
   DEFAULT_GEM_NAME = "the-default-gem" #: String
diff --git a/spec/tapioca/helpers/rbi_helper_spec.rb b/spec/tapioca/helpers/rbi_helper_spec.rb
index 3a9af1d31..b41a2cc5e 100644
--- a/spec/tapioca/helpers/rbi_helper_spec.rb
+++ b/spec/tapioca/helpers/rbi_helper_spec.rb
@@ -5,6 +5,7 @@
 
 class Tapioca::RBIHelperSpec < Minitest::Spec
   include Tapioca::RBIHelper
+  include Tapioca::Helpers::Test::Parallel
 
   describe Tapioca::RBIHelper do
     specify "as_non_nilable_type removes T.nilable() and ::T.nilable() if it's the outermost part of the string" do
diff --git a/spec/tapioca/helpers/sorbet_helper_spec.rb b/spec/tapioca/helpers/sorbet_helper_spec.rb
index ed1b32d6e..554b6d953 100644
--- a/spec/tapioca/helpers/sorbet_helper_spec.rb
+++ b/spec/tapioca/helpers/sorbet_helper_spec.rb
@@ -5,6 +5,7 @@
 
 class Tapioca::SorbetHelperSpec < Minitest::Spec
   include Tapioca::SorbetHelper
+  include Tapioca::Helpers::Test::Parallel
 
   describe Tapioca::SorbetHelper do
     it "returns the value of TAPIOCA_SORBET_EXE if set" do
diff --git a/spec/tapioca/rbi_builder_spec.rb b/spec/tapioca/rbi_builder_spec.rb
index 761e6725f..0d06d11e8 100644
--- a/spec/tapioca/rbi_builder_spec.rb
+++ b/spec/tapioca/rbi_builder_spec.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class BuilderSpec < Minitest::HooksSpec
+    include Tapioca::Helpers::Test::Parallel
+
     describe "Tapioca::RBI" do
       it "builds RBI nodes" do
         rbi = RBI::Tree.new
diff --git a/spec/tapioca/ruby_lsp/tapioca/lockfile_diff_parser_spec.rb b/spec/tapioca/ruby_lsp/tapioca/lockfile_diff_parser_spec.rb
index 4d3b32130..8074ce089 100644
--- a/spec/tapioca/ruby_lsp/tapioca/lockfile_diff_parser_spec.rb
+++ b/spec/tapioca/ruby_lsp/tapioca/lockfile_diff_parser_spec.rb
@@ -7,6 +7,8 @@
 module RubyLsp
   module Tapioca
     class LockFileDiffParserSpec < Minitest::Spec
+      include ::Tapioca::Helpers::Test::Parallel
+
       describe "#parse_added_or_modified_gems" do
         it "parses added or modified gems from git diff" do
           diff_output = <<~DIFF
diff --git a/spec/tapioca/runtime/generic_type_registry_spec.rb b/spec/tapioca/runtime/generic_type_registry_spec.rb
index 47632356f..624053de1 100644
--- a/spec/tapioca/runtime/generic_type_registry_spec.rb
+++ b/spec/tapioca/runtime/generic_type_registry_spec.rb
@@ -6,6 +6,8 @@
 module Tapioca
   module Runtime
     class GenericTypeRegistrySpec < Minitest::Spec
+      include Tapioca::Helpers::Test::Parallel
+
       describe Tapioca::Runtime::GenericTypeRegistry do
         describe ".generic_type_instance?" do
           it "returns false for instances of non-generic classes" do
diff --git a/spec/tapioca/runtime/reflection_spec.rb b/spec/tapioca/runtime/reflection_spec.rb
index 95edd51c3..e8cacc3ce 100644
--- a/spec/tapioca/runtime/reflection_spec.rb
+++ b/spec/tapioca/runtime/reflection_spec.rb
@@ -83,6 +83,8 @@ def unknown_method
     end
 
     class ReflectionSpec < Minitest::Spec
+      include Tapioca::Helpers::Test::Parallel
+
       describe Tapioca::Runtime::Reflection do
         it "might return the wrong results without Reflection helpers" do
           foo = LyingFoo.new