This game lags a lot for me. When I load, save, rollback, etc., the game lags very badly. I have a gaming laptop and it runs windows 8. :/ Wish there was a fix or something for this. It's only this renpy game.
Try shift+G and switching the options there?
Alternatively, try asking on the lemmasoft forum with your logs and full specifications so we can try to help as this may be something specific to your system and the current ren'py version.