Keep ChatGPT responsive during long conversations by collapsing large messages and trimming old DOM elements.
ChatGPT DOM Cleaner is a small Firefox extension that keeps the ChatGPT web interface responsive during long conversations.
If you’ve ever used ChatGPT for coding sessions or debugging help, you may have noticed that after a while the page starts getting slow. Scrolling becomes choppy, typing lags, and memory usage gradually increases.
This extension tries to keep the page manageable by collapsing and trimming older content so the browser doesn't have to keep rendering everything at once.
Why this exists
The ChatGPT web UI keeps the entire conversation rendered in the page. When conversations get long — especially when code blocks, logs, or large pasted files are involved — the browser can end up managing tens of thousands of DOM nodes.
That can lead to:
- sluggish scrolling
- typing delays
- increasing memory usage
- periodic garbage collection spikes
This extension reduces the amount of content actively present in the DOM while still keeping the conversation intact.
What it does
Collapse large pasted messages
If a user message contains a lot of lines (for example when pasting configuration files, logs, or source code), the extension collapses it into a small expandable block immediately after pasting, so it will only take one line of space. If you click it, it will show the original block.
Example:
Expand long message (220 lines)
This keeps large pasted blocks from filling the entire screen while scrolling through the conversation.
Collapse older code blocks
Code blocks from older messages are automatically collapsed once they are far enough away from the newest message.
This makes it much easier to scroll through long coding conversations without constantly passing large blocks of code.
So the entire context becomes readable instead of difficult to follow when looking back for something.
Trim old messages from the DOM
When the conversation becomes large enough, older messages are temporarily removed from the DOM to keep the page lightweight.
Important: messages are not deleted. They are restored automatically if you scroll back up.
Restore messages when scrolling
When scrolling toward the beginning of the conversation, previously trimmed messages are reinserted in small batches.
From the user's perspective the chat still behaves normally.
Pin important messages
You can double-click any message to pin it. Pinned messages are never trimmed from the DOM.
This is useful for things like:
- baseline prompts
- architecture descriptions
- project instructions you keep referencing
Configurable behavior
The popup settings allow you to adjust:
- how many lines trigger text collapsing
- when code blocks should collapse
- how many messages remain visible
- when DOM trimming begins
- soft and hard DOM limits
This makes it easy to tune the behavior depending on how you use ChatGPT.
Example: DOM size before and after
Without cleanup, large ChatGPT sessions can accumulate very large DOM trees.
Typical example:
| Situation | DOM Nodes |
|---|---|
| Fresh chat | ~5k–10k |
| Medium conversation | ~30k–50k |
| Long conversation | 80k–120k+ |
With DOM Cleaner active:
| Situation | DOM Nodes |
|---|---|
| Fresh chat | ~5k–10k |
| Medium conversation | ~20k–30k |
| Long conversation | kept near configured limits |
Keeping the DOM smaller makes scrolling and typing noticeably smoother.
Typical usage scenario
This extension is most useful when ChatGPT is used for:
- coding help
- debugging sessions
- reviewing large configuration files
- analyzing logs
- long technical discussions
These types of conversations tend to accumulate very large blocks of text and code.
Permissions
The extension only requires:
storage
This permission is used to store the settings configured in the popup.
The extension:
- does not collect user data
- does not send network requests
- runs only on ChatGPT pages
Supported pages
https://chatgpt.com/* https://chat.openai.com/*
Installation
Install the signed .xpi file through Firefox:
about:addons → Install Add-on From File
Collapsed code blocks when scrolling back:
Trim the settings best for your own needs:
Long user messages are collapsed immediately:
This extension is simply a small utility intended to make long ChatGPT sessions easier to work with, especially when dealing with large pasted inputs or code blocks.