Yes it used to happen to me  a lot, and I believe to others as well, but haven't seen it recently.

Did this happen while Jotunheim was running.

I noticed some weird stuff happening myself yesterday, particularly as some of the events finished, and then at the end it was like trying to drag the mouse through treacle , rather than sliding on ice

Have you done the usual stuff of cleaning out the cache etc?

true, it happened to me a lot too but it usually gets rectified when I restart the game. Like xyz said try cleaning the cache. It might work.