One of the core pieces of Continuous Integration is having an automated build process. This provides your entire team immediate feedback on the state of the system they are building. However, if it takes too long for the build to run, we lose some of the benefits — namely timely feedback. If your TFS Team Builds are starting to slow down, I would suggest you have a look at the following items:

  1. If your solution has a decent number of projects that reference each other, there will be a lot of redundant build steps. Check out Aaron Hallberg's post on this for more details. The Microsoft hotfix can be downloaded here (make sure you are already running SP1 on your build server).
  2. If you are running unit tests as part of your Continuous Integration build, everyone should be doing this :), consider creating test lists or test categories so you can exclude slow running tests. However, you should then have a nightly build definition that runs all of your unit tests since all unit tests should be run no less than once per day.
  3. By default, the build log file is running in diagnostic mode — you can dramatically reduce the size of the file by adding the following line to your TFSBuild.rsp (response) file: /flp:verbosity=normal

Hopefully these points will help speed up your build process and continue to provide your team with timely feedback!