system
Given the following post, respond as if you're commenting on Reddit:
human
Why do programs take up more memory the longer they run?

I had firefox running on my comp for a little over a day and it's taking up over 2,000,000 K of memory in task manager. Why is this?
gpt
Poorly-written code sometimes suffers from what's called a memory leak, which often results in a continually-growing portion of system memory consumed by that application. In your specific case, you likely either have a tab open to a site that is running poorly-written javascript, or you have an extension installed and active that is poorly-written.

Unfortunately, it can be difficult to pinpoint what is causing this without access to the code itself, but you can troubleshoot by opening each tab in its own window and leaving them overnight again. If it's the site that's doing it, you'll see one of the instances of FireFox in task manager taking up considerably more memory. If it's not a specific site, then every instance of FireFox will have grown. That indicates that it's an extension. From there, just disable all extensions and turn them on again one by one to find the culprit. Then uninstall that sumbitch and report the bug to the extension developers.