Hi everyone — quick post with a practical fix for a performance issue many of us hit during long sessions.
The problem (short)
After ~30–100+ turns, the ChatGPT web UI becomes extremely slow: scrolling stutters, typing hangs, CPU spikes.
The root cause is that the frontend keeps every message rendered in the DOM, even ones far off-screen. Over time this balloons into thousands of active nodes and the browser bogs down.
What I built
I put together a small local-only Chrome extension that applies DOM virtualization to ChatGPT:
it only renders the messages currently in the viewport and swaps off-screen ones with lightweight spacers. When you scroll, the correct nodes are restored instantly.
This keeps the DOM small while still preserving the full conversation history.
Results
Much smoother scrolling, lower CPU/memory usage, and no more UI slowdowns on long threads.
How to try it
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Search for “ChatGPT Speed Booster” on the Chrome Web Store (v1.0.2 is live). Install, refresh ChatGPT, and try a long conversation.
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The extension is intentionally local-only and it doesn’t send your data anywhere.
Open-source
If anyone wants to inspect the implementation or build on it, the code is here:
Github: bramgiessen/chatgpt-lag-fixer
Happy to answer questions about the virtualization logic, MutationObservers, or scroll container handling.