No No No ppl

LimeWire calculates the so called SHA-1 Hash value for each file. In short, a Hash is an unique fingerprint of a file which identifies it among billions of other files on the net.

http://en.wikipedia.org/wiki/Hash_function
http://en.wikipedia.org/wiki/SHA_family

... it's a cryptographic process with a lots of math and there's absolutely no way around it. The slower your computer is the longer it takes to compute the Hash (a dual 2GHz G5 with one CPU maxed out for the Hash function can process for example 70 to 80MB/s and an iBook G3 with 500MHz IIRC 15MB/s -- but the hash function is running in a throttled mode in LW to not eat up all CPU cycles).