Limit CPU Usage in HandBrake

On a Quad-Core add this to the advanced parameters (HandBrake): Code: :threads=3

or this Code: :threads=2

on a Dual-Core machine. HandBrake (HB) uses a lot of SSE2/SSE4 instructions, which saturate the memory I/O system (even on SB-machines), so that virtual cores (HT) are not able to improve the performance of the x264 encoder in HB. That means, you should use Code: :threads=NumberOfPhysicalCPUCores

for maximum performance and Code: :threads=(NumberOfPhysicalCPUCores :threads=(NumberOfPhys icalCPUCores / 2) + 1

for lower temperatures (RAM & CPU semiconductors). +1 is for the I/O thread. Some other tricks: Use the "renice" command (Terminal) (Terminal) to give HB a lower priority: Code: sudo renice 19 PID

"PID" is the process id, which you can find via Activity Monitor or via the Code: top

command in a Terminal window. You can reduce the CPU usage of some apps via the Terminal, if you know you do not need them (a web browser for example): Code: kill -SIGSTOP PID

reduces the CPU usage of the process with the process id "PID" to zero. Code: kill -SIGCONT PID

resumes the process with the process id "PID"