It truly depends on what you do. If you hit plenty of rails, then fat skis will make locking on and switching up feel very laboured. They will be a lot less manoeuvrable and nimble in general on any sort of jib feature.
Performance is affected less on jumps. Once you're in the air, size doesn't really matter, all you have to worry about is swing weight and mount position, not width really. That said, spinning anything past a 7 will increase in difficulty. Inverts, doubles, and fast rotations will all be more difficult simply because pow/AM skis are generally heavier, longer, and mounted further back, so you will feel a different weight distribution when spinning than with a jib ski