One easy way a webmaster can speed up their website is by enabling gzip compression on their web server. Most major websites do this and all modern browsers support receiving gzip encoded content. Sending out gzipped components greatly reduces the size of the response a web server sends to the browser and leads to the user having a faster experience with the website.

Despite this being a plus for everyone, according to the book Even Faster Web Sites,around 20% of US users do not experience this enhancement. The number goes down to 15% when a world wide audience is considered, but that’s still a decent number of web surfers. The book states that the culprits behind the slowing down of the net for 15% of its users fall into two main categories:

• Web Proxies
• Computer Security Software

The reasons for this are that the above want to observe the responses from the web server and don’t want to have to decompress the files, so they either remove or mangle the “Accepts-Encoding:gzip” message that your browser sends to the web server. This leads to the web server thinking that the browser doesn’t support gzip compression, and therefore it sends back uncompressed data. The reason for mangling or stripping away the “Accepts-Encoding:gzip” message may have been to try and minimize the number of CPU cycles needed to examine data from the web server, but increasing download time to get around decompressing data is a poor trade off.

Many newer security software suites have since rectified this problem, but there are still some out there that unnecessarily hamper your web surfing. You can check and see if you’re apart of the 15% of people who don’t recieve gzipped data by going to the following link: Gzip Compression Test Page

I’m writing this entry mainly because I’m doing a lot of front-end optimization at work and I ended up discovering that I was in the unfortunate 15% of web users who were missing out on a faster web experience. I also found out that my parents were in the same boat. If you click the link above and discover you are also not benefiting from gzip compression on the web, it’s worth temporarily disabling your security software and seeing if it is the cause of your problems. If you are unable to isolate the problem to software on your computer, it may be a web proxy which is removing/mangling the “Accepts-Encoding:gzip” message, and if that’s the case, you’re pretty much out of luck unless you control the proxy.

If you isolate the problem to your security suite, I would either try upgrading the software or switching to a different service. I dual boot my machine with Windows and Linux (my problem was only on Windows) and for Windows I’ve currently switched to using Microsoft’s Security Essentials for my virus checker (along with SpyBot), which LifeHacker seems to think is good enough, though I’m currently still researching the best tools to use.

If you are a webmaster and are interested in enabling gzip compression, you can find an easy-to-follow tutorial on how to do it here. If you want to go a little further down the rabbit hole, Yahoo! has put together a very nice list of techniques you can use to speed up your website.