It doesn't take much material to build up the tips, and the shape of the string grooves is really what's important. It should be a tear shape with no sharp corners, ridges or bends - and that includes how it comes off the tips! This is the most overlooked area for bowyers, professional and hobby.
I've gained 8-10fps on every bow I've switched over to low-stretch strings. That's a huge gain - like shooting a bow that's 8-10# heavier.