Performance regression when using the GHC API to evaluate code compared to 8.4

I've been in the process of updating IHaskell to support GHC 8.6 and the test suite has become agonisingly slow as compared to GHC 8.4 and below. I've been able to work around this by using --enable-executable-dynamic as suggested by christiaanb on #ghcbut I thought this was worth reporting as a bug.

To reproduce this on a Linux installation with Nix:

git clone https://github.com/gibiansky/IHaskell
cd IHaskell
git checkout 6058cd4fac01a2023dbd09d174f1f8d4c36e7475
Comment out --enable-executable-dynamic in release-8.6.nix
nix-build release-8.6.nix

Edited Mar 10, 2019 by Vaibhav Sagar

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information