diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..606c80b
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-24 - Memoizing NLP Regex Compilation
+**Learning:** NLP and clinical text evaluation repetitively instantiates the same compiled regexes and lexicons if missing memoization, leading to heavy redundant object compilation overhead.
+**Action:** Always memoize deterministic lexicon object/regex instantiations (e.g. using @functools.lru_cache) and wrap return types in immutables to avoid performance bottlenecks in loops/text processing pipelines.
diff --git a/openmed/openmed/clinical/context.py b/openmed/openmed/clinical/context.py
index 9fd11df..b761125 100644
--- a/openmed/openmed/clinical/context.py
+++ b/openmed/openmed/clinical/context.py
@@ -35,7 +35,9 @@
 
 from __future__ import annotations
 
+import functools
 import re
+import types
 from collections.abc import Iterable, Iterator, Mapping, Sequence
 from dataclasses import dataclass, replace
 from datetime import date
@@ -154,7 +156,9 @@ class _CompiledContextLexicon:
     backward_context_cues: frozenset[str]
 
 
+@functools.lru_cache(maxsize=32)
 def _compiled_context_lexicon(language: str | None = None) -> _CompiledContextLexicon:
+    """Returns a memoized compiled lexicon to avoid repeated regex compilation."""
     lexicon = get_clinical_cue_lexicon(language)
     token_boundaries = lexicon.token_boundaries
     return _CompiledContextLexicon(
@@ -195,7 +199,7 @@ def _compiled_context_lexicon(language: str | None = None) -> _CompiledContextLe
             ),
             token_boundaries=token_boundaries,
         ),
-        category_by_text=_cue_category_lookup(lexicon),
+        category_by_text=types.MappingProxyType(_cue_category_lookup(lexicon)),
         backward_context_cues=frozenset(
             _normalize_cue_text(cue) for cue in lexicon.backward
         ),