Change speed % with more options other than 50% or 100%

[snakex64]

Is your feature request related to a problem? Please describe.
It is much easier to slap 50% print speed versus going to mess in the settings but it can be much slower than necessary.

Describe the solution you'd like
It would be nice to be able to change the speed % to specific values so that I can "compromise" to 75%. Having a smaller in-between pre-made option would also be a nice way of patching this if letting the user specify a custom % is too much work!

[Anthony-Bec]

+1