“Throttle speed to ___% of realtime” option is used to set the highest proxy speed limit. In the result the CPU usage is decreased by increasing the proxy time. Please note, if the proxy speed doesn’t exceed the defined limit, throttling will not work.

"Throttle speed" is used to relieve the system from peak loads.

Sometimes it happens that with rapid rendering of the next chunk, CPU utilization reaches 100%, which negatively affects the work of other modules of the system. If there is a margin for the speed of rendering, you can use "Throttle speed" and thus achieve more smooth system operation, without overloading.