Ok, at first i was confused by this and now I realize you were looking at the results for the case where searching occurs. Im not sure if this is an ideal case to use for comparison tho. I believe that the search routine uses CanEditNode() is not normal. Try a normal page fetch and see the results there. I think the case where search isnt invoked is by far the more common case, so speeding that up is more important than speeding up search.

Having said that obviously you have a point, but i think maybe there is a middle ground to be found where we still cache with node, but more intelligently. IE, if a group does not contain an accessrule then the NODE is not relevent. Anyway, food for thought. :-)

Anyway, thanks for exploring this further, I will do more as well.