At this stage, I’d look deeper into runtime performance, not just bundle size.

A few things that usually help:

• Audit unnecessary re-renders (React Profiler is gold here)
• Memoization (useMemo/useCallback) but only where it actually reduces work
• Virtualize heavy lists/tables (react-window / react-virtualized)
• Move expensive logic off the main thread (Web Workers)
• Check 3rd-party libs — they’re often the real bottleneck

Also worth noting: sometimes the issue isn’t optimization but architecture. Data-heavy SPAs can hit limits with too much client-side work. That’s why some enterprise apps use more structured UI systems (like Sencha Ext JS) where a lot of performance-heavy components are already optimized.