We develop a web application hosted on IIS 7/7.5 (WS2008/2008R2) and now also in 8/8.5 (WS2012/2012R2).
In the iis we have installed also the compression modules (both static and dynamic).
The %Windir%\System32\inetsrv\config\applicationHost.config was modified to compress static and dynamic content.
In IIS 7/7.5 works well, but the same setting not work on IIS 8/8.5
Only the static content is compressed Gzip, the dynamic content is not compressed.
I have tested it in many servers.
So my result is: on IIS 8/8.5 the dynamic compression does not work.
To analyze the traffic we use fiddler.
I have built 2 simple test:
Demo is a WS2008R2
The 2 pages are compressed correctly
http://demo.teradp.com/compression/dynamic.aspx
http://demo.teradp.com/compression/static.htm
Main is a WS2012R2
Only the static is compressed