A MacBook Pro laptop with OS X Yosemite (10.10.5) I've been using today had been performing poorly. When I checked on CPU and memory usage, I found Firefox 38.7.0 was responsible for most of the memory usage and was consuming an excessive amount of CPU cycles. The Activity Monitor application, which is found in Applications/Utilities, showed that Firefox was consuming about 1/2 of the 16 GB of Random Access Memory (RAM) on the system. The Activity Monitor was also showing about 100% CPU utilization by Firefox. If a process is misbehaving, you can kill it with the kill command, but you can also suspend and resume it with the kill command using
kill -STOP pidand
kill -CONT pidwhere pid is the process identifier for the process. I used the command
kill -STOP 509to temporarily suspend execution of Firefox so I could complete some pressing tasks.
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