2-fold memory and 2.5-fold time usage regression from GHC 8.10.4 to 9.01 in the mmark package

Summary

Building mmark-0.0.7.2 with GHC 9.0.1 takes 2 times more memory and 2.5 times longer than with GHC 8.10.4.

Reproduction steps

$ cabal get mmark-0.0.7.2 && cd mmark-0.0.7.2
$ cat > cabal.project
packages: .
package mmark
  ghc-options: -Rghc-timing
^D
$ cabal build

Results

GHC version	Peak megabytes allocated	Mutator CPU time in seconds	GC CPU time in seconds
8.4.4	2839	66.720	30.528
8.6.5	2050	65.112	27.428
8.8.4	2662	63.661	29.302
8.10.4	2581	64.875	30.612
9.0.1	5170	196.415	56.772

As in #14974 (closed), GHC appears to spend most of the time on the Text.MMark.Parser module.

Note that mmark uses -O2.