diff --git a/src/gimkit/dsls.py b/src/gimkit/dsls.py
index 4540116..6720f40 100644
--- a/src/gimkit/dsls.py
+++ b/src/gimkit/dsls.py
@@ -47,7 +47,7 @@ def build_cfg(query: Query) -> str:
     ```python
     query = '<|GIM_QUERY|>The capital of <|MASKED desc="single word" regex="中国|法国"|><|/MASKED|> is Beijing<|MASKED desc="punctuation mark" regex="\\."|><|/MASKED|><|/GIM_QUERY|>'
     print(repr(build_cfg(Query(query))))
-    >>> '%llguidance {}\nstart: "<|GIM_RESPONSE|>" REGEX "<|MASKED id=\\"m_0\\"|>" m_0 REGEX "<|MASKED id=\\"m_1\\"|>" m_1 REGEX "<|/GIM_RESPONSE|>"\nREGEX: /\\s*/\nm_0[capture, suffix="<|/MASKED|>"]: M_0\nM_0: /中国|法国/\nm_1[capture, suffix="<|/MASKED|>"]: M_1\nM_1: /\\./\n'
+    >>> '%llguidance {}\nstart: "<|GIM_RESPONSE|>" REGEX "<|MASKED id=\\"m_0\\"|>" m_0 REGEX "<|MASKED id=\\"m_1\\"|>" m_1 REGEX "<|/GIM_RESPONSE|>"\nREGEX: /\\s*/\nm_0[capture, suffix="<|/MASKED|>"]: T_0\nm_1[capture, suffix="<|/MASKED|>"]: T_1\nT_0: /中国|法国/\nT_1: /\\./\n'
     ```
     """
     num_tags = len(query.tags)
@@ -80,24 +80,34 @@ def build_cfg(query: Query) -> str:
     # 3. Define whitespace rule (named REGEX to match examples, usually can also be called WS)
     lines.append(r"REGEX: /\s*/")
 
-    # 4. Generate specific rules for each tag
+    # 4. Collect unique patterns and create a mapping for terminal reuse
+    # This optimization avoids creating duplicate terminal rules for tags with the same regex
+    unique_pattern_terminals: dict[str, str] = {}
+    terminal_definitions: list[str] = []
+
     for i, tag in enumerate(query.tags):
         # Note: When used with suffix, using greedy match /(?s:.*)/ instead of /(?s:.)*?/ is correct and legal.
         pattern = f"/{tag.regex}/" if tag.regex else "/(?s:.*)/"
 
+        # Get or create a shared terminal for this pattern
+        if pattern not in unique_pattern_terminals:
+            # Create a new terminal name for this unique pattern
+            terminal_name = f"T_{len(unique_pattern_terminals)}"
+            unique_pattern_terminals[pattern] = terminal_name
+            terminal_definitions.append(f"{terminal_name}: {pattern}")
+
+        terminal_name = unique_pattern_terminals[pattern]
+
         # Rule m_i (logical layer):
         # - capture: tells the engine to capture this part.
         # - suffix: specifies the ending tag, the engine stops and consumes it when encountered.
         # Note: Here we reference the TAG_END constant (i.e., "<|/MASKED|>")
-        lines.append(f'm_{i}[capture, suffix="{TAG_END}"]: M_{i}')
-
-        # Rule M_i (regex layer):
-        # Define the actual matching pattern for this tag.
-        lines.append(f"M_{i}: {pattern}")
+        lines.append(f'm_{i}[capture, suffix="{TAG_END}"]: {terminal_name}')
 
-        # TODO: There may be many tags with "/(?s:.*)/" pattern, which can be inefficient.
+    # 5. Add all unique terminal definitions
+    lines.extend(terminal_definitions)
 
-    # 5. Assemble final string
+    # 6. Assemble final string
     grammar = "\n".join(lines) + "\n"
 
     is_error, msgs = validate_grammar_spec(get_grammar_spec(grammar))
diff --git a/tests/test_dsls.py b/tests/test_dsls.py
index 10190e7..ee085bf 100644
--- a/tests/test_dsls.py
+++ b/tests/test_dsls.py
@@ -14,8 +14,8 @@ def test_build_cfg():
         "%llguidance {}\n"
         'start: "<|GIM_RESPONSE|>" REGEX "<|MASKED id=\\"m_0\\"|>" m_0 REGEX "<|/GIM_RESPONSE|>"\n'
         "REGEX: /\\s*/\n"
-        'm_0[capture, suffix="<|/MASKED|>"]: M_0\n'
-        "M_0: /(?s:.*)/\n"
+        'm_0[capture, suffix="<|/MASKED|>"]: T_0\n'
+        "T_0: /(?s:.*)/\n"
     )
     assert build_cfg(query) == grm
 
@@ -25,8 +25,8 @@ def test_build_cfg():
         "%llguidance {}\n"
         'start: "<|GIM_RESPONSE|>" REGEX "<|MASKED id=\\"m_0\\"|>" m_0 REGEX "<|/GIM_RESPONSE|>"\n'
         "REGEX: /\\s*/\n"
-        'm_0[capture, suffix="<|/MASKED|>"]: M_0\n'
-        "M_0: /\\w+\\.com/\n"
+        'm_0[capture, suffix="<|/MASKED|>"]: T_0\n'
+        "T_0: /\\w+\\.com/\n"
     )
     assert build_cfg(query_with_regex) == whole_grammar_regex
 
@@ -37,6 +37,29 @@ def test_build_cfg():
     ):
         build_cfg(Query(MaskedTag(regex="[[]]")))
 
+    # Test with various complex patterns including repeated regexes
+    query = Query(
+        "Date: ",
+        MaskedTag(id=0, regex=r"\d{4}-\d{2}-\d{2}"),
+        ", AnotherDate: ",
+        MaskedTag(id=1, regex=r"\d{4}-\d{2}-\d{2}"),  # same as id=0
+        ", Time: ",
+        MaskedTag(id=2, regex=r"\d{2}:\d{2}:\d{2}"),
+        ", AnotherTime: ",
+        MaskedTag(id=3, regex=r"\d{2}:\d{2}:\d{2}"),  # same as id=2
+    )
+    assert build_cfg(query) == (
+        "%llguidance {}\n"
+        'start: "<|GIM_RESPONSE|>" REGEX "<|MASKED id=\\"m_0\\"|>" m_0 REGEX "<|MASKED id=\\"m_1\\"|>" m_1 REGEX "<|MASKED id=\\"m_2\\"|>" m_2 REGEX "<|MASKED id=\\"m_3\\"|>" m_3 REGEX "<|/GIM_RESPONSE|>"\n'
+        "REGEX: /\\s*/\n"
+        'm_0[capture, suffix="<|/MASKED|>"]: T_0\n'
+        'm_1[capture, suffix="<|/MASKED|>"]: T_0\n'
+        'm_2[capture, suffix="<|/MASKED|>"]: T_1\n'
+        'm_3[capture, suffix="<|/MASKED|>"]: T_1\n'
+        "T_0: /\\d{4}-\\d{2}-\\d{2}/\n"
+        "T_1: /\\d{2}:\\d{2}:\\d{2}/\n"
+    )
+
 
 def test_build_json_schema():
     query = Query(