The -fno-semantic-interposition flag significantly improves startup time for dynamically linked binaries by disabling support for symbol interposition (e.g. LD_PRELOAD. We should evaluate whether we think the loss of LD_PRELOAD functionality is justified by the performance gains. If we decide against doing so, we should consider building with -fsemantic-interposition, since clang defaults to -fno-semantic-interposition despite it generating binaries that are technically not in alignment with the ELF standard.