I’m sorry you are encountering performance issues with the app and your Mac. RAW Power uses the GPU almost entirely which can be an issue for older Macs. In addition, Apple has introduced a new GPU library called “Metal” which sometimes has issues on older hardware. (mouse freezing is an indication that the GPU is overloaded)
Please try the following. Step 1 is to disable Metal.
1) Go into RAW Power > Preferences
2) Switch the GPU to OpenGL:
3) Important: Quit and reopen RAW Power.
If that doesn’t address the issue, please switch the CPU / GPU export setting in Preferences.
Using the CPU for export further decreases the work the GPU has to do.
I hope this helps.