PPSSPP options explained

[Furby]

(I made a topic about this earlier, but I think I may get a better response here)

Why is it, when I'm on my mobile devices, I'm able to get a higher VPS with speed set to "Unlimited" than on any other setting?

On my two mobile devices, none of them can, normally, run any game above 20-40 VPS normally, no matter the game (Generalizing, but it works for the visual). However, with the speed set to unlimited, I'm able to achieve a VPS of at least 80 in most cases.

I was under the impression that the settings didn't change anything but the max possible VPS, with Standard being at 60, Fixed being at what you define it in settings, and unlimited being, well, unlimited. But that's clearly wrong. I don't notice any real visual or audio artifacts (Besides, obviously, the "too fast" gameplay) like when I enable frameskipping, so I know it's not doing that. What exactly is unlimited changing in the emulator itself to enable these speeds (And what is it sacrificing in order to achieve this, because I can't see anything)?