It's fine to leave godmode on. But if it took too long to kill enemy, the system resyncs you.
It's also fine to set game speed to 10x. You'll get resync issue at 1.0x game speed too.
The damage multiplier is the big factor to resync issues. If you're too weak and raise it to 100x, get stronger first and reduce the multiplier. If you're too strong, lower the multiplier.