[voidfiles]

With such a complicated system I think you are missing out on the most signifcant speed optimization technique; reducing http requests.

For reference: http://developer.yahoo.com/blogs/ydn/posts/2007/04/rule_1_ma...

It's laudable that you are paying attention to caching, but you don't compile all your files in to one file. It seems like you could pick up a lot ground here by at least concating all css into one file, and js in to one file.

Also you could load jquery from the Google AJAX API endpoint. That way the users has a higher chance of having already loaded jQuery.

Also using the same CSS/JS products across multiple pages would help.

[autoref]

An excellent point, but you have to consider warm cache vs cold cache optimizations. For a cold cache, it's better to combine assets and reduce HTTP requests. We do that on our homepage.

For a warm cache, it's better to split assets up so they are cached in finer chunks. If I added jQuery in to every page JS, there would be few HTTP requests but it would pull jQuery every time, making the payload much larger. There's a balance. I'll write another post about warm vs cold cache optimizations soon.

"using the same CSS/JS products across multiple pages would help."

Definitely. Using jQuery on half your site and YUI on the other half is pretty bad from all angles.

"you could load jquery from the Google AJAX API endpoint."

Yeah. Two reasons we don't: 1. I'm in security, and trust no one. 2. HTTPS connection reuse vs negotiation with another host. I have yet another post in the pipe about SSL optimizations.

[codeka]

I usually have three "chunks" of CSS/JS per page, one for CSS/JS that's shared across all pages of the whole site, one that's common among a "group" of pages and one that's unique to just that page.

Of course, not all pages get all three chunks, but I find it's a reasonable tradeoff between reducing the number of requests and not just including everything on every page.

[seriocomic]

Hmm, i've just left a comment suggesting combining assets. Based on what you've written here you've already answered one of my questions... I look forward to the warm/cold cache post.