In our company we are using ADFS with SP2010.We did an Analysis of the authentication process of ADFS with SP2010.
We found OOTB Signing Page (_login/default.aspx) takes some time to process. It downloads about 400KB of content (Images,CSS) and code(JS) that seems not related to authenticating. Rather it seems for content authoring and editing. This is all due to how OOTB "Simple.master" file is made.
So is it advisable to make a custom master page for this default.aspx? If so, how do i know what bare minimum JS and Placeholder controls are needed for authentication?