Sudden stuttering

[A smol Shinx]

Haven't played this in a while, never beat it, decided to come back to it.
Started over and noticed immediately that I get a very prevalent stutter/hitch every few seconds. Happens on any map, at any time, and so far no setting change I've done in game or in my control panel fixes it. It wasn't like this before. Anyone know why?

[Perseus]

Have you tried verifying the integrity of game files? (Library -> Right-click on game -> Properties -> Installed Files -> Verify integrity of game files)