For people that come here looking for an answer... after invoking the build using the Product > Perform Action > Build with Timing Summary, once the build is done, select the build in the Report Navigator (⌘9) and then selecting Editor > Open Timeline. This will open the timing summary along side the build log. Note that as far as I know, the flag ShowBuildOperationDuration is only used for showing the duration of the build in the toolbar; it is not required to be set for the build timing summary.