Message Filtering Creates O(n²) Rendering Performance Issue

[BP602]

Problem

Message filtering recalculates entire message array on every render, creating O(n²) complexity with large chat histories.

Impact

• Frame rate drops below 30fps with >100 messages
• UI lag during active chat periods
• Exponential performance degradation with message count

Root Cause

// MessagesHandler.jsx:27-37 - Recomputes entire filter on every render
const filteredMessages = useMemo(() => {
  return messages.filter((message) => {
    // Runs for every message on every update

Solution

1. Implement virtual scrolling with react-virtuoso
2. Pre-index messages by chatroom for O(1) lookup
3. Use incremental filtering instead of full recomputation

Success Criteria

• Maintain 45+ fps with 1000+ messages
• O(1) message filtering implementation
• Virtual scrolling with windowing

Files to Modify

• src/renderer/src/components/Messages/MessagesHandler.jsx
• Add virtual scrolling components

Priority: P1 (High)
Estimated Effort: 3-4 days