Generating package images is relatively expensive, but for most users that's worth it as packages are more frequently imported than compiled. Not so for PkgEval, which generally only imports a package once after precompiling it. That's why PkgEval runs with --pkgimages=no, taking about 12h to test all ecosystem packages.

However, now that more stdlibs are being excised from the system image, running with --pkgimages=no results in e.g. the REPL and package manager being recompiled over and over, regressing PkgEval times to ~20h. As a stop-gap solution, we're running with the default --pkgimages=yes now, making sure the stdlib pkgimages can be used. PkgEval now takes ~15h to complete.

Seeing how this is still a 25% regression, and many more packages time-out now, it would be great if we had something like #50586 for pkgimages. With --pkgimages=existing, stdlibs would be loaded from precompiled pkgimages, but we wouldn't be generating new images for the package we're testing.

cc @vchuravy