If you want to look deeper, You have to build elm-compiler by yourself with profiling option.
In short, you should get newest cabal and ghc8.6.5 by ghcup, clone the elm-compiler repo, and build it with cabal v2-configure --enable-profiling; cabal v2-build. (Probably you need cabal v2-install --only-dependencies before first cabal v2-build)
These pages may help. How to profile? · Issue #5930 · haskell/cabal · GitHub Tutorial: Profiling Cabal projects – Functional programming debugs you