LightSession for ChatGPT Fix slow, laggy ChatGPT tabs in Firefox. LightSession is a small, local-only extension that keeps long conversations fast by trimming old messages from the page while your real chat history stays on OpenAI’s servers. Why ChatGPT gets slow When you keep one ChatGPT conversation open for a long time, the page DOM grows with every message. Over time this can cause:

choppy scrolling;
typing delays in the input box;
high CPU and memory usage;
the whole Firefox tab feeling sluggish.

How LightSession works LightSession runs only in your browser:

Watches the ChatGPT page and removes older DOM nodes.
Keeps only the last N messages visible (1–100, configurable).
Waits until a response has finished streaming before trimming.
Pauses trimming while you scroll up to read history.

Removed messages are not deleted from ChatGPT. They are just removed from the current page. If you want to see the full conversation again, simply reload the tab — ChatGPT will load the whole history from the server. Features Performance

Fixes slow / laggy ChatGPT tabs in Firefox
Automatic trimming of old messages in long chats
Efficient DOM updates designed to stay within the 16ms frame budget

User experience

Simple popup UI: enable/disable with one toggle
Choose how many recent messages to keep (default: 10)
Optional “Refresh” button in the popup to reload full history
Works on both chat.openai.com and chatgpt.com

Privacy & security

100% local processing — no extra network requests
No data collection, no analytics, no tracking
Source code is open and available on GitHub

Usage

Install the extension and open ChatGPT in Firefox.
Click the LightSession icon in the toolbar.
Turn on “Extension enabled”.
Set how many messages to keep.
Use ChatGPT as usual — trimming happens automatically in the background.

To restore the full conversation at any time, click “Refresh” in the popup or reload the page. Open source LightSession is open source. Issues, feature requests and contributions are welcome: https://github.com/11me/light-session https://exts.dev/lightsession/

Emil K

Published Firefox add-on:

LightSession Pro for ChatGPT