UCCNC has 48 macroloops, which are similar to mach3's macropump. These apparently run independently, and can be any speed you want. There's an example in the manual for running at 20Hz. Apparently, the faster they run, the higher the CPU loading?
They don't mention the screen refresh, but it's independent of the macros, and appears to be much faster than mach3, as the DRO's are much smoother. The toolpath display is different, so hard to compare. But the entire interface seems much faster.