max_length check optimization

patch.diff

diff --git a/pontoon/checks/libraries/pontoon.py b/pontoon/checks/libraries/pontoon.py
index fb80d3f4..1f284222 100644
--- a/pontoon/checks/libraries/pontoon.py
+++ b/pontoon/checks/libraries/pontoon.py
@@ -13,6 +13,7 @@ from pontoon.sync.formats.ftl import localizable_entries
 
 MAX_LENGTH_RE = re.compile(r'MAX_LENGTH:( *)(\d+)', re.MULTILINE)
 parser = FluentParser()
+html_parser = HTMLParser.HTMLParser()
 
 
 def get_max_length(comment):
@@ -38,22 +39,22 @@ def run_checks(entity, string):
     resource_ext = entity.resource.format
 
     # Prevent translations exceeding the given length limit
-    max_length = get_max_length(entity.comment)
-    html_parser = HTMLParser.HTMLParser()
-    string_length = len(
-        html_parser.unescape(
-            bleach.clean(
-                string,
-                strip=True,
-                tags=()
+    if resource_ext == 'lang':
+        max_length = get_max_length(entity.comment)
+        if max_length:
+            string_length = len(
+                html_parser.unescape(
+                    bleach.clean(
+                        string,
+                        strip=True,
+                        tags=()
+                    )
+                )
             )
-        )
-    )
-
-    if max_length and string_length > max_length:
-        checks['pErrors'].append(
-            'Translation too long'
-        )
+            if string_length > max_length:
+                checks['pErrors'].append(
+                    'Translation too long'
+                )