compile times are extremely high

[MangoIV]

With ghc9.4.6 the compile times for small modules are really high (multiple minutes), is this expected or might this be a regression in the compiler?

[ocharles]

Unfortunately this is somewhat known, but we don't really know what the root cause of the issue is. At CircuitHub, we tend to set -O0 on modules that take a significant amount of time to compile. Can you try that and see if it helps at all? It's unlikely Rel8 modules really much from an optimization, afaik.

[remeike]

So I've encountered similar issues with compile times. It didn't really hit me until my application had to build via a CI pipeline, where it would slow to a halt and max out my memory budget. I was able to narrow the issue down to records that were deriving Generic and Rel8able and noticed it got slower with larger records. Removing all optimizations with -O0 also did the trick for me, however I wanted to figure out which optimizations in particular might be causing the problem. After a bit of trial and error I found that it had something to do with the interface files being generated by GHC. By adding just these two pragmas, -fomit-interface-pragmas and -fignore-interface-pragmas, while keeping all of the other optimizations, I was able to get my compile times down dramatically and resolve the memory leak.

[gbaz]

We ran into the same issue, to the point of making the project effectively uncompilable on some users laptops, and the pragmas flags suggested by @remeike did the trick. This really should be added to the main rel8 documentation.

Just toss this on top of the file defining the rel8able instance:

{-# OPTIONS_GHC -fomit-interface-pragmas #-}
{-# OPTIONS_GHC -fignore-interface-pragmas #-}