#11666: Severe performance degradation in GHC 8.0.1 compared to GHC 7.10.x -------------------------------------+------------------------------------- Reporter: mrkkrp | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While working on a project, I have noticed that GHC 8 takes too long to run my test suite on CI server, see for example here: https://travis-ci.org/mrkkrp/zip/builds/113059190 GHC 8 finished in 370 [seconds](https://travis-ci.org/mrkkrp/zip/jobs/113059197#L599), while GHC 7.10.3 in [82 seconds](https://travis-ci.org/mrkkrp/zip/jobs/113059195#L608), 7.10.2 and 7.10.3 demonstrated similar results (77 seconds). There are minor differences in versions of libraries used, mainly those that are shipped with GHC, I read their changelogs and it seems like it's not likely that this sort of slow-down (× 4.5) happened because of one of those libraries. Note that due to the nature of the project I test it does fair amount of IO in temporary directories, I'll be happy to provide more information if you like. BTW, here is the test suite: https://github.com/mrkkrp/zip/blob/master/tests/Main.hs -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11666 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler