I know it sounds obvious, of course it does, not setting the atime of each file accessed or touched by a program sounds like a certain speedup for somethings.

 but the problem is, how much of an improvement is there?

 stats please! I'd like to see your reasoning about this further than "of course it would work" cause I am sure there are lots of things which "look" like they would improve performance but in real practice dont do any actual difference.

 Just look at STL containers like <vector> lots of people think that using them are slow, they say that "of course plain old arrays are faster!!!! they dont have all that STL  junk" yet actually, they dont realise that in reality, it's not faster at all and it's actually more bug prone and the same speed (if you have a good compiler).

 So! with that said: stats please! lets see your proof.