sadly i can't investigate further, because for 2.1 betas i didn't keep sources for every release.
my fault.
anyway, also if HFS process uses the CPU, doesn't mean it is hfs.exe itself.
other software, like netlimiter, run inside other processes, with dll.
this is also a base method for fooling firewalls
since it happens also with another software, i would tell it is netlimiter itself.
netlimiter is a very nice software. i would use it if it was free.
but sadly, working at a such low level can easily generate incompatibility.