I try in the past and its rival Growl for windows. I found snarl take less system resource than Growl but it have less customize option. The bad thing i think , it is you need several plugin and some apps dont support it , so you need install more and more programs who takes more and more ressource. There a long way yet between both and growl for mac
actually the use of plugins makes perfect sense. or do you want your precious resources used by code for apps that you do not use? btw: if you care so much about ressources, you should definately not run apps like Pidgin that need GTK runnning in the back.