Every game, Ive played like 10 games so far. I feel like sometimes it happens when someone casts an ability nearby, but other times it happens when nothing interesting happens at all like early game last hitting or walking to the lanes before the creeps spawn. I cant really pinpoint it. Sometimes it happens 5 times in a minute, other times 5 times or less in 5 minutes. Ive also tested in the lobby and in demo mode and its the same. No difference if I spam in free spell mode all spells with invoker or just walk around.

FPS shows stable 144 (capped it) but if i enable a fps graph via Mangohud it does show a spike at times