Beacon refreshs effects too slowly

Just today all of the beacons in my minecraft world start recycling / refreshing very slowly. Normally, once the timer gets to 4 seconds it resets to 8. However, it now seems to be taking 12 seconds, i.e. letting the effect expire and waiting 4 seconds for it to kick in again. Besides the general impact of losing all effects for that time, any speed effect is very disconcerting as your view keeps zooming in and out.

This happens at every base I have a beacon at, just started today. Did a game / java restart, as well as a full system reboot.

I've attached a forced-crash report from my main base.