Let's see. Just assume the perlmonks.org is the fastest server in the world, and it replies to requests instantly (as we all notice). I still have a roundtrip time to perlmonks of about 100ms. That's the time that's always lost to do a request. (For the sake of the argument, I leave off the processing time of the proxy I'm using). I also get a throughput of about 75kb/s. That means, in 100ms, you could have added an extra 7.5kb. That would be more than 200 of those headings.

Note that I'm not suggesting to not use CSS. But using CSS to "save bytes" sounds like premature optimization. If you want to save bytes, turn off the nodelets for AMs. Remove the stupid image in the top right hand corner (approx. 60 CSS headers worth of savings). And most of all, turn off the ads. (Well, not for me, I've taken care of that on a much lower level (aka /etc/hosts)).