Xcode 4 too many clang processes

With references to the following question speeding up xcode builds, the following command still works in Xcode 4:

defaults write com.apple.Xcode PBXNumberOfParallelBuildSubtas开发者_如何学运维ks 4

However it only limits the number of 'cplus' processes that Xcode initiates while building. In Xcode 4 now I also get a ton (more than the number of cores I have) of the 'clang' processes, which eat up a lot of memory and freeze my system. So is there any way to limit the number of 'clang' processes while building?

The answer is here: https://devforums.apple.com/message/545348#545348

defaults write com.apple.dt.Xcode IDEBuildOperationMaxNumberOfConcurrentCompileTasks 4

what worked for me in Xcode5, having the same issue (freezes on archiving on last file) is to change the Build Settings: Set "optimisation level" for RELEASE (or all) to NONE. worked wonders.