Make Sure You're Compressing What You Send to the Browser
This is really a tip for IIS 7 (or later) Web site administrators than it is for developers: Make sure that you've looked at how you're using urlCompression your site. urlCompression ensures that, when the browser supports it, your Web pages and static resources (PDF files, for example) are compressed before being sent to the user. This can reduce the amount of bandwidth used on each user request.
There are three compression options and, since IIS 7.5, the most useful one (dynamic compression, which compresses your Web pages) should be turned on by default. Having said that, I had a client running IIS 10 where even that option was turned off. You probably want to ensure that dynamic compression is turned on and, if your users download a lot of files from your site, that the other choices are turned on also.
However, there are a number of options to manage here and the highest compression settings aren't necessarily the best ones (higher compression settings require more processing time and the savings in bandwidth might not compensate for that processing time). In fact, if you're tight on CPU cycles but have lots of network bandwidth to spare you might actually be better off by not using compression. The best discussion that I've found about the various tradeoffs is here (though the post is rather old).
Posted by Peter Vogel on 08/25/2016