I've been having problems like you do on my laptop for so long as well, but no one seemed to care about it. Sometimes, a restart is fixing it, another user on reddit told me to turn off shader cache. I think it improved the whole experience a bit ,but it introduced stuttering. It used to happen after 1-2 hours of gameplay but since the latest update it has become so random, and it seems to be specific things that trigger it. From my understanding, it happens when looking at some certain tiles/objects, frametime goes up but go back to normal when you don't look at it.
Edit: And it looks that sometimes when you zoom in with right click it sets everything back to normal.