[GHC] #10800: vector-0.11 compile time increased substantially with 7.10.1

[GHC]

#10800: vector-0.11 compile time increased substantially with 7.10.1
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by erikd):

 I have ghc 7.8.4, 7.10.3 and 8.0.0.20160316 installed on my machine. I
 cloned the vector git repo, set up a cabal sandbox and then for each ghc,
 `cabal install --dependencies-only`. Them for each ghc I did `cabal clean
 && time cabal build`.

 I've timed this with each compiler three times and this result is pretty
 representative:

 {{{
 Compiler             real         user        sys
 ----------------------------------------------------
 7.8.4            3m26.106s    4m42.508s    1m40.868s
 7.10.3           4m32.690s    6m18.956s    3m6.416s
 8.0.0.20160316   1m19.510s    1m52.796s    0m47.992s
 }}}

 It seems this partially fixed between 7.10.1 and 7.10.3 anyway, and 8.0 is
 far better than either of the old releases.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10800#comment:12>
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