If you want to use your computer for other tasks besides the running analysis, you can optimise the working speed.
Set a low priority for the engine. For UCI engines this can be done via the dialog "Create UCI engine", where you can set a lower priority.
Alternatively, in the settings dialog you can set a lower value for the threads than the actually available cores. For example, on a quad core you could set the value 3. This ensures that one core remains available for the other applications running in parallel.