Any programmer could've told you that a system juggling more than one task looses time to context switching and interrupts, which a system that focuses on one task only has to waste time switching when a task is over.

On the other hand, you will notice lulls due to blocking, when a resource isn't available, yet. The single-tasked system has to wait and waste time. The multitasked system can switch to something else (and wait for the interrupt later).