TeamCity 8.0.2 bugfix build is available now. It addresses several important issues and regressions, as well as some performance problems. We strongly recommend that you upgrade to this version, especially if you experienced problems with TFS, email notifications or slow builds finish. Additionally, there are general enhancements increasing the server performance.
If you upgrade from version 8.0, installing 8.0.2 build preserves the data format (this is usually the case with all our bugfix builds). In case you encounter any problems with build 8.0.2, you can safely revert to 8.0.1 or even 8.0 without the need to restore from backup.