Evaluate performance using different compilers and flags

[achains]

1. Choose a preferable tool for profiling, you should be able to ground your choice (e.g. google orbit, gprof, valgrind+kcachegrind)
2. Compile project using gcc/clang, try different optimization flags
3. For every chosen settings make performance notes into the table (chosen compiler and flags, overall performance, lowest speed part of the code)