https://issues.dlang.org/show_bug.cgi?id=11229 --- Comment #12 from Jon Degenhardt <jrdemail2000-dlang at yahoo.com> --- Ascii check optimization for asLowerCase and asUpperCase in this commit: https://github.com/dlang/phobos/commit/f257e8330e5babbf5c74325dc32a2886bd181f02 --