I installed EZ-Power for two of our local sporting clubs some years ago, and I recently noticed that one was very fast when switching between Categories, and the other took a relatively long time to refresh the screen when changing between categories, even though the Computer's specifications were the same. Even on a high performance PC, the screen updates were unacceptably low on the second installation.
The slower of the two had 137 Product images, and some of them were around 400kb in size.
As a test, I bulk downsized the images to a height of 250 pixels (15-64kb) with Corel Paintshop Pro, and suddenly my screen updates when changing Categories was nice and fast again. The image resolution was still more than adequate.
I hope this tip may be of benefit to others....
Cheers
John - in Sunny Carnarvon, Western Australia.