It depends on how many bytes you need to move per frame
I do not remember actual figures but I was able to move the whole pnt (768 bytes) safely ina frame.
A key factor is having your data in vram arranged in order to use few vdp commands.
iirc i succeded in moving the pnt with only 8 HMMM copies
Wait a second. Isn't it so that these commands only work on the V9958 if I am to use them for screen4!!??
I guess so, see Artrag's first line in the link I posted for the way to use it.
On msx2 you need to switch to screen 5 or screen 8 in hblank, send your vdp commands and return to screen 4 after the vdp has finished. Note that the vdp will stop the command execution if you return to screen 4 before it has finished. This implies that the excecution time of vdp commands has to fit the hblank time, or if your scorebar is in screen 5, the hblank time + the scorebar time.
on msx2+ and TR (V9958 ) there is a bit in some status register that allows you to use vdp commands even in screen 2/4 like it was screen 8, but in that case you do not need tricks and you do not have timing problems
http://www.msx.org/news/software/en/vscreen-optimization-test
here there are few data about performance
