I have the same problem. Its painfully slow. Even when I leave the machine and comeback, it seems like it has accomplished nothing.
I was wondering if this is because of the computer or just the program itself. I am using an old 486, so I though that was the problem. But if you still have the same issue with a 550MHz machine... I'm running DOS 6.1 and TurboCNC is all that is running on it.
I find it goes faster if curves and circles are coded with G02 or G03 instead of a bunch or G01 lines (like, from CAM software). But it stops every quarter circle even then.
If this is what can be expected from TurboCNC, I'd love to know. Because, if so, I'm switching to something better. I love the simplicity of the program, but it just too slow.