In 7u4 tiered compilation has been made default. We have seen mixed results in terms of performance in the testing we've done but the data has not been conclusive and has mostly pointed to very small regressions. In addition to that we've seen improvements in startup performance for several types of applications.
Over the last week we have received more reports from FMW performance testing that show (very) significant regressions. Many mid-sized workloads seem to work fine, but at least for some large ADF based workloads response times go up enough to cause test failures. The FMW performance team will recommend FMW/FA to turn off tiered compilation by explicitly disabling it.
In addition to this we've also seen regressions in startup time for short-lived applications.