Modern SEO is typically related to the CSS (Cascading Style sheet) because the buzz is coming around that site speed would matter most to rank your site in SERP.
First of all your site should be loaded within 1 second (this variable differs)to attract potential visitors, otherwise you get lost in terms of traffic generation. CSS is the ultimate solution (external CSS obviously) by pre-defining your all attribute syle in a separate file and main HTML will be light, so the page-load time get the boost.
If this is the buzz you are hearing, then swat that bug away because it is just NOT true. Site speed is at most a small factor - something like a tie breaker. It will never have more importance than relevance and trust signals.
In addition, it is not just the download speed of the HTML document that matters, it is the entire time it takes for a user to render a page - and that includes any external CSS files. This is predominantly measured by Google toolbar data.
Please don't buy into this kind of buzz - it's just more mythology in the making and we've already got too much SEO mythology as it is.
Here's some reference material from Google's Matt Cutts:
Google is incorporating site speed as one of the over 200 signals that we use in determining search rankings...
...fewer than 1% of search queries will change as a result of incorporating site speed into our ranking.
...please don't worry that the effect of this change will be huge.
Site speed is at most a small factor - something like a tie breaker.
No-one else thinking that Google's announcement that speed is a factor is just a way to reduce the load on their bots? Announce it, then say, but don't expect to see any changes as a result ... suspicious to say the least! ;)
and if the webmaster tools graphs are anything to go by
They're not. Although, I blocked that basefarm.net crawling network and my GWT speed graph now puts my loading time at a 3rd of what it used to be.
Never new basefarm.net was messing up my servers so much!
I doubt it, IH. If that was the story, why go to all the trouble (and it is a LOT of trouble) of measuring rendering speed, rather than simple bandwidth? Googlebot doesn't render anything, it just caches the source code. Most of the recommendations about page speed have no effect on file size.