HoustonFirefox

I installed this today and while the thumbnails looked much better it does not appear to be cacheing any of them since I can view the items under a given category, switch to a different category (waiting for the picture generation) and then going back to the original category just to sit and wait for the thumbnails to be re-generated. What directory would I check to see if thumbnail files are being generated? Any help? I'm relatively new to osCommerce and have been all over the documentation for OSC as well as this contribution but can't find out why the browsing is so slow. Thanks in advance for any assistance, HoustonFirefox