Looks like random, I can get it in a world with small amount of lights and constructions, but when amount of light and constructions are large it become more noticeable. On previous version same world didn't give any such lag spikes
Not sure what could cause this... If you run into these lag spikes again (especially if it's happening more frequently), could you maybe send us a report? So we can check at least if there is maybe an error occurring in the background