Dear user,
i usually use limewire pro 4.18.8.
Monday 8.12.2008 i have installed an old version of limewire
the LimeWire 4.12.6 (it's a basic version).
I found this version light, but more light than the new version.
Why ? It seem to work better than the pro version ...

Yes possibly. Though I should warn you .. as of the LW beta version 4.17.4 & later, all later versions will not upload to versions earlier than 4.14. So eventually you will not get too many successful downloads as the number of people using pre 4.17 becomes less. O.o Changelog - LimeWire

It's always been the case, one particular version runs better on some people's systems than others.