I set the tick speed really high to test the copper degrading, but all that seemed to do was make commands unresponsive. Breaking and placing blocks seemed fine though, and no lag was introduced. System fans did not speed up. World saving took a lot longer than usual, so it was killed via MultiMC.
actions used in order:
world creation
messing around with creative
/gamerule randomTickSpeed 1000000000
[commands unresponsive past this point]
/gamemode spectator
/weather thunder
/gamemode spectator
/weather thunder
world saving
instance killed via MultiMC
Duplicate of MC-76117 which is marked as Works as Intended. Don't put your Tick Speed at high levels