Enabling GZIP will have much more effect than minifying your HTML, anyway.
Doing minification at runtime could hurt your servers (assuming you don't use caching). It may be a good idea to minfiy your Asp.Net markup during deployment. This way, you still have a non-minified version of code in your code repository, and a minified version on the server. Think of a deployment process where you invoke an HTML minifier (for instance, this tool by Dean Hume looks promising) on all .aspx
files.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…