http://chuchusoft.com/par2_tbb/download.html
It got an update to version 20141125 with several changes.
Among them are:
the -t parameter can now include a positive integer value to restrict the logical number of CPUs with which to process data with.
in the Windows version, the program's CPU scheduling priority can now be specified using the -p parameter
the heap became fragmented during the verification of data files because the checksum data buffer was allocated and deallocated for each file verified, which resulted in the program's memory footprint (aka its "working set") steadily increasing during the verification phase.