diff --git a/apisix/core/table.lua b/apisix/core/table.lua
index 60b0a6eba739..dd767859fd4c 100644
--- a/apisix/core/table.lua
+++ b/apisix/core/table.lua
@@ -31,6 +31,7 @@ local pairs        = pairs
 local type         = type
 local ngx_re       = require("ngx.re")
 local isarray      = require("table.isarray")
+local str_has_prefix = require("apisix.core.string").has_prefix
 
 
 local _M = {
@@ -130,7 +131,8 @@ do
         copied[orig] = copy
         for orig_key, orig_value in pairs(orig) do
             local path = parent .. "." .. tostring(orig_key)
-            if opts and array_find(opts.shallows, path) then
+            if opts and (array_find(opts.shallows, path) or
+                (opts.shallow_prefix and str_has_prefix(parent, opts.shallow_prefix))) then
                 copy[orig_key] = orig_value
             else
                 if type(orig_value) == "table" then
diff --git a/apisix/plugin.lua b/apisix/plugin.lua
index a2898bc0d404..afdf50f0bb2f 100644
--- a/apisix/plugin.lua
+++ b/apisix/plugin.lua
@@ -818,7 +818,10 @@ local function merge_consumer_route(route_conf, consumer_conf, consumer_group_co
         return route_conf
     end
 
-    local new_route_conf = core.table.deepcopy(route_conf)
+    -- the plugins subtree is fully overwritten below, so there is no need to
+    -- deep-copy it; shallow-copy that subtree to avoid the wasted work
+    local new_route_conf = core.table.deepcopy(route_conf,
+        { shallow_prefix = "self.value.plugins" })
 
     if has_group_plugins then
         for name, conf in pairs(consumer_group_conf.value.plugins) do
diff --git a/t/core/table.t b/t/core/table.t
index 38616ae535bf..52e55162ee51 100644
--- a/t/core/table.t
+++ b/t/core/table.t
@@ -359,3 +359,37 @@ tab_copied.a.b.c == tab.a.b.c1: true
 tab_copied.a.b.c == t1: true
 tab_copied.x.y == tab.x.y: false
 tab_copied.x.y == t2: false
+
+
+
+=== TEST 13: shallow_prefix
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local plugin1 = {name = "plugin1"}
+            local plugin2 = {name = "plugin2"}
+            local tab = {
+                plugins = {
+                    p1 = plugin1,
+                    p2 = plugin2,
+                },
+            }
+
+            local tab_copied = deepcopy(tab, { shallow_prefix = "self.plugins" })
+
+            tab_copied.plugins.p1 = {name = "plugin1_new_modified"}
+            tab_copied.plugins.p2.name = "plugin2_modified"
+
+            ngx.say("table copied: ", require("toolkit.json").encode(tab_copied))
+            ngx.say("table original: ", require("toolkit.json").encode(tab))
+        }
+    }
+--- request
+GET /t
+--- response_body
+table copied: {"plugins":{"p1":{"name":"plugin1_new_modified"},"p2":{"name":"plugin2_modified"}}}
+table original: {"plugins":{"p1":{"name":"plugin1"},"p2":{"name":"plugin2_modified"}}}
+--- no_error_log
+[error]