diff --git a/frappe/__init__.py b/frappe/__init__.py
index 7c71bc8815..c4f4b2a690 100644
--- a/frappe/__init__.py
+++ b/frappe/__init__.py
@@ -15,6 +15,7 @@ import importlib
 import inspect
 import json
 import os
+import re
 import warnings
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Union
 
@@ -45,6 +46,10 @@ STANDARD_USERS = ("Guest", "Administrator")
 
 _dev_server = int(sbool(os.environ.get("DEV_SERVER", False)))
 _qb_patched = False
+re._MAXCACHE = (
+	50  # reduced from default 512 given we are already maintaining this on parent worker
+)
+
 
 if _dev_server:
 	warnings.simplefilter("always", DeprecationWarning)
diff --git a/frappe/model/db_query.py b/frappe/model/db_query.py
index fe52818235..82913db98d 100644
--- a/frappe/model/db_query.py
+++ b/frappe/model/db_query.py
@@ -40,6 +40,16 @@ CAST_VARCHAR_PATTERN = re.compile(
 	r"([`\"]?tab[\w`\" -]+\.[`\"]?name[`\"]?)(?!\w)", flags=re.IGNORECASE
 )
 ORDER_BY_PATTERN = re.compile(r"\ order\ by\ |\ asc|\ ASC|\ desc|\ DESC", flags=re.IGNORECASE)
+SUB_QUERY_PATTERN = re.compile("^.*[,();@].*")
+IS_QUERY_PATTERN = re.compile(r"^(select|delete|update|drop|create)\s")
+IS_QUERY_PREDICATE_PATTERN = re.compile(
+	r"\s*[0-9a-zA-z]*\s*( from | group by | order by | where | join )"
+)
+FIELD_QUOTE_PATTERN = re.compile(r"[0-9a-zA-Z]+\s*'")
+FIELD_COMMA_PATTERN = re.compile(r"[0-9a-zA-Z]+\s*,")
+STRICT_FIELD_PATTERN = re.compile(r".*/\*.*")
+STRICT_UNION_PATTERN = re.compile(r".*\s(union).*\s")
+ORDER_GROUP_PATTERN = re.compile(r".*[^a-z0-9-_ ,`'\"\.\(\)].*")
 
 
 class DatabaseQuery(object):
@@ -343,8 +353,6 @@ class DatabaseQuery(object):
 		As field contains `,` and mysql function `version()`, with the help of regex
 		the system will filter out this field.
 		"""
-
-		sub_query_regex = re.compile("^.*[,();@].*")
 		blacklisted_keywords = ["select", "create", "insert", "delete", "drop", "update", "case", "show"]
 		blacklisted_functions = [
 			"concat",
@@ -368,19 +376,14 @@ class DatabaseQuery(object):
 			frappe.throw(_("Use of sub-query or function is restricted"), frappe.DataError)
 
 		def _is_query(field):
-			if re.compile(r"^(select|delete|update|drop|create)\s").match(field):
+			if IS_QUERY_PATTERN.match(field):
 				_raise_exception()
 
-			elif re.compile(r"\s*[0-9a-zA-z]*\s*( from | group by | order by | where | join )").match(
-				field
-			):
+			elif IS_QUERY_PREDICATE_PATTERN.match(field):
 				_raise_exception()
 
 		for field in self.fields:
-			if sub_query_regex.match(field):
-				if any(keyword in field.lower().split() for keyword in blacklisted_keywords):
-					_raise_exception()
-
+			if SUB_QUERY_PATTERN.match(field):
 				if any(f"({keyword}" in field.lower() for keyword in blacklisted_keywords):
 					_raise_exception()
 
@@ -391,19 +394,19 @@ class DatabaseQuery(object):
 					# prevent access to global variables
 					_raise_exception()
 
-			if re.compile(r"[0-9a-zA-Z]+\s*'").match(field):
+			if FIELD_QUOTE_PATTERN.match(field):
 				_raise_exception()
 
-			if re.compile(r"[0-9a-zA-Z]+\s*,").match(field):
+			if FIELD_COMMA_PATTERN.match(field):
 				_raise_exception()
 
 			_is_query(field)
 
 			if self.strict:
-				if re.compile(r".*/\*.*").match(field):
+				if STRICT_FIELD_PATTERN.match(field):
 					frappe.throw(_("Illegal SQL Query"))
 
-				if re.compile(r".*\s(union).*\s").match(field.lower()):
+				if STRICT_UNION_PATTERN.match(field.lower()):
 					frappe.throw(_("Illegal SQL Query"))
 
 	def extract_tables(self):
@@ -910,7 +913,7 @@ class DatabaseQuery(object):
 		if "select" in _lower and "from" in _lower:
 			frappe.throw(_("Cannot use sub-query in order by"))
 
-		if re.compile(r".*[^a-z0-9-_ ,`'\"\.\(\)].*").match(_lower):
+		if ORDER_GROUP_PATTERN.match(_lower):
 			frappe.throw(_("Illegal SQL Query"))
 
 		for field in parameters.split(","):