What is LTO?

LLVM features powerful intermodular optimizations which can be used at link time. Link Time Optimization (LTO) is another name for intermodular optimization when performed during the link stage.
LTO seeks to reduce or eliminate duplicate calculations, inefficient use of memory , improve performance in programs containing many frequently used functions of small or medium length.
Its now used by famous custom kernel devloper kdrag0n , kerneltoast ,YaroST12 and other.