Overview
Here’s the guide for those who are experiencing low fps and lags in cutscenes. Hope you’ll find it helpful.
How to fix
Select unlocked in maxfps option on graphics setting. This will make your game not locked on certain fps. And for fixing cutscene lags, open Steam in big picture mode and run Sonic Forces. Tadaa! The game is running much better than before.
Now there are mods for reducing graphics quality for low-end systems. You can use them if you are experiencing low fps or lags.