Mastodawn

@peterkotrcka you can try https://support.mozilla.org/en-US/kb/task-manager-tabs-or-extensions-are-slowing-firefox and see if an addon starts using too much resources after day or two.

Task Manager - see whether tabs or extensions are slowing down Firefox | Firefox Help

Firefox has a feature that lets you see how much memory and CPU resources are being used by tabs, extensions and other processes. Learn more.