1. Check the number of files in the hand history folders. If there are a lot of files (thousands and tens of thousands), this may affect the speed. Move the old files to other folders and check the speed after that. If this is the case, clean out your folders from time to time.
2. If you uploaded the hand history through the Verification tab, this may take up RAM and affect the speed. To reset, log out on the Settings tab or end the program through the task manager.