How to change data on the metabase of IIS 6

First you'll need to enable the metabase editing. You can do it like this
Then you'll need to install the metabase editor

Once you can change metabase data you can do stuff like enabling gzip compression, removing/changing the IIS banner.

Web site performance - don't forget the gzip

if your web server is not in a CPU intensive situation and your bandwidth is high (even for some assets like image/javascript files) you should consider using the HTTP compression - GZIP.

read how to get it done on Microsoft techNet