I paused when I read Intel compiler - that thing is a steaming pile of crap, or at least was for godawful number of releases for a long time and I don't expect it to ever work in the real world with a non-trivial amount of C++ code base. And then I read about a Mozilla header causing it to ICE! Years ago, I was forced to make a company's product faster by "simply" recompiling it with ICC. It was losing in the benchma…
For numerical code, ICC is amazing. But that's mainly because the automatic vectorization is far beyond anything clang can spit out (which is already better than gcc at automatic vectorization).
Even then, icc really benefits when you use its proprietary pragmas for hints.
The VTUNE profiler is amazing though