Depends.. some plugins are very intense on the usage. Cambridge3 EQ is 4% dsp while fairchild is 16%...Nigel is crazy at 33%.. Dream Verb is 19%.. 1176LN is 14% 1176SE is 5%.....Channel Strip is 9%... All other basic ones are 4-5....etc.

Basically, If you want to run efx on each track without rendering them down you need multiple cards... I always tweak and render and move on...

(You also have to be careful of going tto 100% usage as you computer might freak out (but not necessarily crash)