New Hitfilm versions are really laggy

So I've been using hitfilm 13 until a few days ago, when I decided to see all the things that changed and ever since I downloaded the newest version the program is lagging/stuttering really bad. Sometimes it crashes by doing a single cut, and if it doesn't instantly crash it freeze lag for at least 5 seconds...

So is there any way to fix this, or to get my old version back since it's not really fun (or possible) to do anything like this.

Thanks for advice in advance.