I had posted a request for repos with slower compile times a few weeks back (Repos with slow compile times wanted for research), and I got around to writing up a bit on what I found.
The TL:DR of it is if you run your build with elm-make +RTS -s -RTS src/Main.elm and see a lot of time being spent in garbage collection (“GC” in the output), you can build your own version of elm-make that should dramatically improve speeds.
Thank you for this. I had lost the links to your compiled binaries.
Thank you so much for this. Such an improvement to the development process when things are more responsive. A real game changer!
I love how complicated “just give the process enough memory to work with” can be. 
Why is it necessary to use Haskell 7.10? I’m not using Haskell for anything else so installing an old version is not a problem, but if I did want the latest I’d rather not have to learn how to run multiple versions at the same time.
And if i understand correctly I need to add -rtsopts to the compile options - where do those go in the https://github.com/elm-lang/elm-platform/blob/master/installers/BuildFromSource.hs file?
elm-compiler master is already on 0.19.
I think the best course of action right now is to use the provided binaries and wait for 0.19 
Anyone having any success with the Linux binary at https://github.com/antew/node-elm-compiler/releases/download/elm-make-files/elm-make.linux.x64? I get
~/applications/elm-make.linux.x64 +RTS -A128M -H128M -n4m -RTS Main.elm
elm-make.linux.x64: Most RTS options are disabled. Link with -rtsopts to enable them.
which is what I get with the standard version
Sorry about that @simonh1000, I’ve updated the binary and tested it with a little dockerfile
FROM node
RUN curl -sL "https://github.com/antew/node-elm-compiler/releases/download/elm-make-files/elm-make.linux.x64" -o /elm-make && chmod +x /elm-make
RUN curl -sL "https://github.com/antew/node-elm-compiler/releases/download/elm-make-files/LongListMatch.elm" -o /LongListMatch.elm
RUN /elm-make --yes +RTS -s -A128M -RTS LongListMatch.elm
It should work correctly now!