Steve,
As a first off, without knowing more about what the switch is doing its difficult to say whether high memory utilisation is to be expected or not. Having said that you should save the output from a show tech and enter it into the output interpreter and see what it comes back with.
You may find you are running a known "buggy" version of IOS that has specific memory leaks which results in high utilisation.
It usually makes some suggestions for further monitoring to understand the cause behind the high utilization.
Its usually a good starting point. If the switch is running fine, and has always experienced this level of utilisation then its unlikley to be a problem and could just be a feature.
Regards
Steve