profiler VS heaptrack

Probably your best bet is to use the Firefox Profiler once it starts hogging the CPU to try to see what it's doing. I'd be happy to take a look at the result although I don't have a lot of experience at diagnosing performance problems; hopefully the profile will make it obvious what's going on.

I tried using the https://profiler.firefox.com/ and running with:

You can try to reproduce while taking a profile using the Firefox profiler, then share it in the #perf:mozilla.org room on Mozilla's Matrix instance.

Run a profiling session for ~30 sec when you notice something is running slower than you expect, see https://profiler.firefox.com/. Share results here if you want help interpreting them.

Next time, send a SIGABRT to the main process (kill -6 $(pidof firefox)) and use the resulting backtrace (you will find a link to the crash report in about:crashes) to file a bug. A performance profile could be useful, but you'll need to know first what to capture. This seems like a graphics issue, so try the Graphics preset. Share a link to your report.

https://profiler.firefox.com will be useful if you can capture and share it to developers.

If you can reproduce it in safe mode and a clean profile, capture a performance profile using the clean profile while trying to load a problematic webpage, don't remove any information from it, and share it here (although it's typically not easy for users to analyse them), or file a bug with it attached.

Next time, capture a performance profile using the Graphics preset, and kill the browser by entering kill -6 $(pidof firefox) in a shell. This will create a bug report (unless debian disables the crash reporter) that would indicate where Firefox is stuck at. You might need to use an official build to get useful results.

If we are talking replacing the libc allocator, then something like heaptrack is worth mentioning.

https://github.com/KDE/heaptrack

For accurate memory usage I prefer a memory profiler that overrides malloc and friends instead of the ones that probe the OS at regular intervals. You won't find memory spikes with the latter. Try heaptrack on Linux. I haven't found a good one for Windows yet.

I know it is not a profiler, but it is so criminally underrated that I decided to share it: https://github.com/KDE/heaptrack

If none of the above helps - I recommend heaptrack as a tool for tracking down your memory usage.

> memory leaks. It's surprisingly hard to find an easy to use memory leak detection tool.

I can vouch for heaptrack[1] nowadays, although it's pretty much Linux only. It's under the umbrella of KDE, but a heaptrack trace only requires a CLI app, and there is a nice Qt viewer to analyse the memory consumption.

It tracks the memory utilization at the level of malloc'd/free'd bytes. It's fine if your memory leak or other memory utilization problem is on this level. Recently I dealt with an issue, where increasing memory utilization was caused by fragmentation within the allocator. This didn't show up in heaptrack as an increasing memory utilization, but heaptrack still pointed out where most of the temporary allocations happened, leading to the culprit of the fragmentation.

[1] https://github.com/KDE/heaptrack

This is probably what you are looking for https://github.com/KDE/heaptrack

When I had this kind problems (heap related) I always use heaptrack. Take a look here for the details: https://github.com/KDE/heaptrack