Mission: Optimize Team Build bringing sources for all of the branches while it builds either the head or one of the branches.
Current time to build: 30 minutes of average solution of 50 medium sized projects.
Customize the team build project file to initialize the build workspace differently so server source control (tfs) binding is pointing directly to the branch/head folder not the root one.
For example our root would be: $/Project/Apps which corresponds to the head. Then branches are: $/Project/Apps_RB_1, $/Project/Apps_RB_1. When building the head it was getting the source for the whole $/Project/. Very slow and expensive IO for our TFS.
TODO: Add samples.
At the end, having solution implemented but not progressing here with any more info, as team build 2008 seems to have this problem resolved and you can narrow what you get to what you really need (at least as announced).