perf: Remove markdown serialize from editor render path (#3567)

* perf: Remove markdown serialize from editor render path

* fix: Simplify heading equality check

* perf: Add cache for slugified headings

* tsc

app/scenes/KeyboardShortcuts.tsx

@@ -445,4 +445,4 @@ const Label = styled.dd`
   color: ${(props) => props.theme.textSecondary};
 `;
 
-export default KeyboardShortcuts;
+export default React.memo(KeyboardShortcuts);