Why is checksumming so much slower on a sparc64?

[Chris Ross <cross+netbsd%distal.com@localhost>]

  I have two netbsd-6 machines, running nearly the same code.  One is an i386 
with 2.8ghz-ish processor(s), and one is an UltraSPARC-IIIi with a pair of 1.5 
ghz processors.

  When trying to build vim from pkgsrc, the checksum checks on all of the 600+ 
files for the i386 takes a second or two.  Where as, each of the pair of 
checksums seems to take more than a second.  I *think*, inferring from the 
output rate, that the SHA1 is fast, and the RMD160 is what's taking more than a 
second for each file.

  Why is this?  This can't be an insurmountable issue, can it?

                         - Chris