LLVM Clang 3.4 SVN Compiler Optimization Level Tests
For the HMMer scientific workload, there was a very significant difference between no optimizations (-O0) and the first optimization level (-O1) but after that, there were barely any performance improvements with the higher optimization levels.
For some of the GraphicsMagick imaging operations, the results were similar to HMMer with seeing no real change after the first compiler optimization level for LLVM Clang 3.4 SVN.