You should be able to - but I'm not sure on the implications when someone's doing a transaction.

Are there alot of products? I found that reorganising the categories sometimes helps, as does PageBlaster - http://www.snapsis.com  It does a great job with caching and makes browsing considerably faster.  I found it made quite an impact on the sites I'm running it on but their issues were different, rather than traffic based, it was image size and depth of categories in one page that I felt slowed it down.

It's not just catalook either - I've found a few sites that allow up to three categories deep with thousands of products and menu items appearing on a single page really is quite inefficient.

I've got a support forum for catalook on http://www.catalooksupport.com - there are a few people who also know about Catalook who chip in and answer questions.  

Nina Meiers

It is ok to recycle your aspnet process every 60 minutes if you are ok with the startup time.