First point, you shouldn't be using on of the beta versions of HostFS2. The correct one to use is the one supplied in the "HostFS Jan 2009 Update". Manually messing with components can easily cause problems as you can end up with incompatable bits
Did you follow my instructions and go and download and install all the updates from the VirtualAcorn website?
The ProcessorPriority value is set to 0 by default as this is correct for 90%+ of machines. Where a machine has lots of other stuff running that has a higher prioroty then it is sometimes necessary to increase the value of the ProcessorPriority flag. This is because is some circumstances VRPC can not get the CPU cycles it needs to keep the
emulation thread running correctly. The clock speed of the machine doesn't have much bearing on this. The number of cores does. A quad core machine will be able to run a lot more at the same time than a dual core machine. So, the problem is being caused by other app(s)/services that are being run on the machine.