I'm running Linux Mint 22.3 on an older MacBook Pro with an Intel i5 and 16 GB of RAM. I switched to Linux because macOS had become sluggish, and Mint initially felt much faster. Recently, though, all four CPU cores can reach 100% during fairly ordinary use, such as browsing with around ten tabs while keeping a few applications open. Since the workload seems light for this hardware, what should I check to identify the cause and improve performance?
3 Answers
Firefox can legitimately use quite a bit of CPU with multiple tabs, video, heavy websites, or extensions, but 25–90% while mostly idle suggests investigating further. Try disabling extensions one at a time, checking the browser's task manager, and comparing CPU usage with a clean profile or another browser. Thunderbird can also spike while indexing or synchronizing mail, so check whether it settles down after those tasks finish.
Start with System Monitor or run htop and watch which processes are actually consuming the CPU. The browser, extensions, background services, or another application may be responsible. Check whether the usage stays high after closing Firefox and other programs, since the solution depends on the process causing it.
A CPU reaching 100% is usually not something an optimization tweak fixes; first determine what is using the processor. If the load comes from an unexpected process, look for a bug, runaway service, or software rendering. Video playback is worth checking for hardware acceleration. Also monitor temperatures and clock speeds, because overheating can cause the processor to throttle and make normal tasks feel slow even when the CPU is fully occupied. If the workload is legitimate, reducing tabs, extensions, or background applications may be the practical solution.
Firefox often sits somewhere between 25% and 90% with about ten tabs open, and I also see a cinnamon process using roughly 25%. Thunderbird sometimes contributes too. I'll test the extensions and compare with another browser rather than assuming the desktop itself needs replacing.