Just caught up on this thread. I felt youcoming started to get you in the right direction, or certainly it was similar to what I was thinking anyway! The cadence is important, but along with that is the resistance you have while pedaling, you shouldn't need to "mash", but if you are spinning at 80+, you are not mashing. As long as your cadence is at a reasonable level, you should ask yourself "how much resistance do I have? Could I change up to the next highest gear and, with a little effort, still spin at 80+?" If yes, then do it! This is relevant in places where you wouldn't really think about it. It is for when your hill starts to flatten out, yes you are a little tired from having climbed the worst of it, but rather than relax as it becomes easier, if you think about it, you could start going into higher gears again and keeping a good cadence. The same for when you crest a hill and begin down the other side, fast riders will go through the gears and ride down the hill, not roll down it. You should be pedalling downhill unless you reach "escape velocity". (Refer to Rule #23).

It may take a bit of practice, but always getting that right balance will make you faster. Pedal at a decent cadence, but at the same time, you should always feel your pedalling is helping to drive the bike forward.

Hope that makes sense!