Severe performance regression in v1.0.0

I am testing updating the build of doldecomp/melee from wibo 0.7.0 to 1.0.0 and am noticing a huge (~25x) slowdown in the new version.

Before (0.7.0):

$ time ninja
<snip>
Executed in   25.31 secs    fish           external
   usr time  339.17 secs    0.38 millis  339.17 secs
   sys time  148.99 secs    1.26 millis  148.99 secs

After (1.0.0):

$ time ninja
<snip>
Executed in  632.48 secs    fish           external
   usr time  139.64 mins    0.20 millis  139.64 mins
   sys time   78.02 mins    1.70 millis   78.02 mins

Note that I am not using prebuilt static wibo binaries - I am building using Nix and dynamically linking against system libraries (libclang, mimalloc). https://github.com/doldecomp/melee/blob/8a5d975fbd3debea3db7aa5f4851aea5222d5344/.nix/wibo.nix
That being said, I am doing this for both 0.7.0 and 1.0.0 and I don't think that alone can explain such a severe performance regression.

Edit: I have updated the build to use the project-provided statically-built wibo-i686 from the releases page and can confirm a similar slowdown.

Start by reproducing the reported ninja build slowdown with wibo 0.7.0 and 1.0.0, using both the Nix configuration in .nix/wibo.nix and the project-provided statically built wibo-i686 binary. Compare the builds and execution measurements to identify where the regression occurs; done means the cause is isolated and the v1.0.0 performance is verified against the earlier release.