pico: Don't sleep when we need to render

[Daft-Freak]

We could end up missing frames if update doesn't take much time.

Fixes an empty update/render sometimes missing frames in hires and improves logo modified to use hires mode to get a constant 25 FPS instead of sometimes falling to ~16 (it also has an empty update).

[Gadgetoid]

Makes sense, thank you!