pollerThreadCount's description is: The number of threads to be used to run for the polling events. Default value is 1. Can't see a reason to go above that. But experiment and find your own results. The code appears to default to Runtime.getRuntime().availableProcessors() which may be one, but in many cases is not.
Thanks for the report. This has been fixed in trunk and 6.0.x and will be included in the next release.