Sorry for the delay: I was on break from extra-curricular coding.

Anyway, I ran some benchmarks and it looks like using a multiple of the number of CPUs is marginally faster.  You can find the raw data here: http://sdrv.ms/11ATzS9.  These results are hardly scientific since they are specific to my machine and all the specifics of its configuration, but it's what we have.

You could make a case for bumping the number up to numCPUs*3 (it is the fastest on most tests) or leaving it at numCPUs (it is only trivially slower in some of the tests, but is less taxing on the system memory and is less likely to cause issues with limits being hit).  You could also make a case for setting it to min(numCPUs, 10), since number of logical processors does not necessarily correlate with more memory.

If you have an idea for further benchmarks to run, just let me know as I'd be happy to do them.  If not, feel free to just weigh in on what you think we should do and I'd be happy to adjust the code accordingly.

Thanks!