If you haven’t already heard, Yahoo! has released YSlow for Firebug, a Firefox plugin that analyzes your site for ways to speed things up in terms of HTML, CSS and JavaScript.

I installed it an hour ago and it gave my site a performance grade of D with a score in the low 60’s. After a few small tweaks, my grade is B and my score is 83. My blog should be noticeably faster to load.

The first thing it recommended I do (an “F” on Reduce DNS lookups) was to strip a number of the third-party JavaScript features I’d added over time in order to reduce the number of domains my site referenced. I removed the Technorati, Skype and Twitter JS calls because, well, they really don’t add much value. I changed my Site Meter code to use the non-JavaScript version - which also had the benefit of removing attempts to ping specificclick.net which sets a third-party tracking cookie (Google for more details - some people feel Site Meter should have been more open about this change).

I also got an “F” for ETags. Reading the Yahoo! site (linked from the YSlow plugin) gave me the Apache magic necessary to disable those (in my .htaccess file):

FileETag none

I have a “B” now because the Developer Circuit widget still has an ETag.

An “F” in Expires header scoring became a “D” after I enabled Expires headers for CSS and images (again, in .htaccess):

ExpiresActive On

ExpiresByType text/css “access plus 1 month”

ExpiresByType image/jpeg “access plus 1 month”

ExpiresByType image/gif “access plus 1 month”

My Gzip components scored improved to a “B” by adding a directive to deflate CSS:

AddOutputFilterByType DEFLATE text/css

Another tweak I made that seemed to help was adding defer=”defer” to the Developer Circuit JavaScript include - the only third-party JS left on my site now.

The only remaining “red flag” - my one remaining “F” - is the recommendation to use a CDN which isn’t really available for free to folks like you and me.

If Developer Circuit adds a few Expires headers, enables Gzip and disables ETags then my site will get faster still but I’m impressed with what I’ve been able to do in a short space of time.

Thanx Yahoo!

p.s. Also thanx to John Farrar who was the first person to notify me about YSlow!