This is indeed a very strange bug: supply and ordnance capacities for planets of more than 1000000 seem to cause the problem. But why only for simultaneous games??
I'm suspecting the ship is losing another one of its critical control components. Likely due to skip armor/null-space weapon damage. I saw dozens of combats with v1.77 and never noticed the rapid weapon fire bug, so I don't think it's happening outside of a critical component being lost.