The Free number

It shows how much free cpu power you have. If it is > 0, then your game runs at 60fps.

If you see it jumping very quickly all the time, then it most probably means that you are running another program in the background which is eating your cpu power. Raine is very sensitive to this in multitasking environements because it synchronises with the rdtsc counter of the cpu which will never slow down, no matter how loaded your cpu is. A java applet in the browser can eat a lot of cpu power for example !