[x-post from Reddit reply] Thanks so much for all the hard work! Unfortunately I have a compile time performance regression to report on my FLTKHS https://github.com/deech/fltkhs library. I also don't have a minimal example. There is a demo that took about 15 seconds compile and link in 7.10.3, but with no changes now takes over a minute in 8.0.1. I've reproduced this across machines and operating systems. Since there was interest expressed in using this example as a benchmark if any GHC devs are still willing to help, I'm willing to walk them through getting the library set up etc. It's not a long process. The tip of my Github branch has been updated to build with GHC 8.0.1. I made myself a Trac account but apparently I don't have Ticket privileges so it won't let me create one. My username is 'deech'. Thanks! -deech