Slowness in AJAX loaded controller

[groenroos]

I have a custom made controller in my shop (Prestashop 1.4.7.3, Apache/2.2.3 (CentOS), PHP version: 5.3.3, MySQL version: 5.0.95), that's used as a modified category controller loading all products in a category to a single template, attribute selections and add to cart buttons and all.

 

The products can be filtered with two dropdowns, that create GET attributes to the URL.

 

These divs are hidden via CSS, so only one product is displayed at a time, and the divs are toggled via JS.

 

All of this is loaded via AJAX into an overlay on the index page.

 

However, the problem I have with it is that it's super slow. Loading times for the overlay average around 9 seconds, and can get up to 15. Obviously this is an issue when you want to browse several overlays quickly.

 

You can see it live at http://www.zoouniform.com - just click on the animal faces on the main page to bring up the overlay.

 

What could be the reason behind the slowness? The server isn't amazing, but none of the other pages are as slow. I have caching and all other performance boosts on. I can't upgrade Prestashop version (at least very easily) since I've done heavy and uncharted modifications to the core code.

 

Any resolution to this? Thanks a lot in advance!