Platform-injected scripts causing severe scroll jank (Reddit pixel + vendor bundle blocking 9s on main thread)

[rockcandymountaincharlie-arch]

I've been experiencing severe scroll jank on desktop in my app (Battle Command) on the Player Registry page, which uses @tanstack/react-virtual to virtualize a list of ~130 player cards.

After extensive debugging — trying virtualizer config changes, overscan tuning, refetch interval removal, React.memo comparators — nothing improved scroll performance. I finally ran Chrome DevTools Performance profiler during a scroll session and found the root cause is not in my app code.

Here's what the profiler showed:

Summary (14 second recording):

• Scripting: 1,894ms
• Rendering: 117ms
• Painting: 48ms

The rendering and painting costs are normal. The scripting cost is the problem.

Bottom-up breakdown of main thread time by source:

• pixel.js (Reddit pixel): 1,489ms main thread time
• vendor-ui-Cyp-Rc9O.js (Base44 UI bundle): 977ms total, 85.9% of Function call time
• base44.com (1st party): 242ms

The Reddit pixel analytics script and your vendor UI bundle are running heavy JavaScript continuously on the main thread, which competes directly with scroll rendering and causes frames to freeze for 1,300ms–9,700ms at a time.

This is not something I can fix in my app code. The third-party scripts are loaded by the Base44 platform, not by me.

Could you please investigate:

1. Why the Reddit pixel is loading in app previews and whether it can be deferred or removed
2. Whether vendor-ui-Cyp-Rc9O.js can be optimized or code-split to reduce main thread blocking during scroll

I'm happy to share the full profiler recording or screenshots if helpful.