I too had a sticky throttle, not only did I have some crap under the throttle tube, but the linkage was also a bit grimey (including a cable end seized in the TB). It would get worse the hotter the bike got.
A liberal application of WD40 to all the moving parts, plus one-seizing the cable end, made it butter smooth, and it's really really obvious that it's made a difference. You can also check your throttle free play and cable tension is correct, too tight and it can feel sticky.