If UCCNC has LookAhead settings, I'd try raising the number of lines the controller looks ahead; this is what will general "smooth" out motion, in conjunction with CV.

There are g-code optimization software that will fit arcs from multiple segments. Some expensive CAM have this feature as well. Some not-as-expensive CAM will do arc optimization in the X-Y plane (Z waterline toolpath). Some CAM will generate 3D arcs and NURBS, but only the more expensive controllers can handle that. Some CAM and g-code optimization software can also switch the controller between exact stop and CV. Some CAM and g-code optimization will also adjust the feedrate (and DoC) to maintain spindle loads - when approaching an inside corner for example.

As you can imagine, this can greatly decrease the program line count, and decrease machining time. It will also decrease the money in your wallet a LOT. But, leave a smoother finish on your part.

I will say, you should use "stock" toolpaths (2.5D) whenever possible, and 3D toolpaths only whenever necessary (never use it to pocket for example).