Bertrude, from the feedback I have received, the speed of a virtualized FreeHand is as fast as it is on your Snow Leopard. Basically running Snow Leopard in Parallels or Fusion is no different speed-wise or with using Xtras. The problem is swapping files with Mavericks apps since drag-and-drop doesn't always work. I understand that Parallels is better at this but I don't have it installed.
Normally there is a shared folder that you put your files into to pass them back and forth with Mavericks. I do this with Sheepshaver pretty easily using earlier versions of FreeHand.
I saw a good comparison of Fusion and Parallels at Macworld.com but don't have the link. A search on their site should find it. By their review, Parallels was the better of the two because of passing files but it was very close with Fusion. Plus these two companies are constantly improving their features.
I am going to test VirtualBox, which several FreeHanders have had good results with. I hope to have some news on this next month.