I can confirm that using your code exactly as posted, I can compile RFC1213-MIB from the test suite under v5.8/NT4 and perls memory usage never (quite) reaches 6MB, so it looks like a local problem on you Win32 box rather than an inherent problem with either the module or the OS.

Suggestions: Try the same test I did, if that fails it's probably your installation of SNMP::NIB::Compile so blow it away and re-install, though as it's a stand-alone, pure perl module it difficult to see how that could be wrong.

If the testcase works, then look closely at the file(s) your compiling. Are they really the sam eas those on you Solaris box? Do you have any circular dependancies?