Earlier this week Yahoo! released a public version of an internal website performance tool called YSlow. Visit the YSlow page for instruction and downloads. YSlow runs on Firefox and requires the Firebug extension. I’ve used YSlow a lot to help improve the Messenger web sites, so I’m pretty familiar with its operation. I can see where some people using it on either personal blogs or smaller sites will be surprised a the somewhat harsh grading for things like using a CDN. For a large site with huge traffic like Yahoo, it’s a no-brainer, but for a small blog it doesn’t…