Compiler memory usage regressions for aeson in GHC 8.8 and 9.0.1
# Summary
Peak memory allocations for building `aeson-1.5.6.0` increased by ca. 100% from GHC 8.6.5 to 8.8.4 and by another ca. 50% from 8.10.4 to 9.0.1.
# Reproduction
```
$ cabal get aeson-1.5.6.0 && cd aeson-1.5.6.0
$ cat > cabal.project
packages: .
package aeson
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 | 947 | 133.281 | 44.035
| 8.6.5 | 968 | 135.371 | 45.080
| 8.8.4 | 1928 | 132.890 | 47.662
| 8.10.4 | 1973 | 135.847 | 47.235
| 9.0.1 | 2944 | 153.501 | 67.389
Note that `aeson` uses `-O2`.
issue