Performance Monitor

TeamCity provides a build feature called Performance Monitor that allows to get the statistics on CPU, disk and memory usage during build run on build agent. When enabled, each build has an additional tab called PerfMon at the build results page, where this statistics is presented as a graph. You can also click on points in chart to see the corresponding part of the build log.

For example, from the picture below it is clear that at some point CPU and Disk usage is very low. This lasts for about 20 minutes. Seems like the tests executing at this time need some investigation, probably, most of the time they are blocked on some lock or wait for some event:

Performance monitor supports Windows, Linux, Solaris and MacOS X operating systems. Note that performance monitor reports the load of the whole operating system. It will not report proper results if you have more than one agent running on the same host, or agent and server installed on the same machine.