After site growing in products we hit slowdown issues, after much worry and stress it turned out to be cache tag issues.
Uploading a single file and enabling it in local.xml then completely and utterly revolutionizes the speed of the site.
We are talking moving from 2 to 3 second category/product page to 400ms, and moving from 4 or 5 second+ for add to cart/checkout to around 800ms.
So my question is... what is the catch? Why is this not standard functionality in CE?