The wording isn’t the clearest and details aren’t given, but I’m pretty confident uwestoehr is saying single-threaded PackageCompiler takes longer (~40%) and often fails with errors on v1.11.4 compared to v1.10.9 for something. To broadly speculate, some third-party package developers have reported slower compilation, larger caches, or slower loading, which could be related to any of the big internal changes in v1.11 which PackageCompiler can’t directly do anything about; the silver lining is precompilation at least only has to be paid once per unique environment and there are people invested in improvements.