[2023-01-18 20:48:56-0500] Joshua Kinard:
So is adding a default definition of TZ to our base system /etc/profile something we want to look at? I haven't tried any other methods of benchmarking to see if not making those additional syscalls is just placebo or if there are actual impacts. Given how long this oddity has been around, I can't tell if it's a genuine bug in glibc, an unoptimized corner case, or just a big nothingburger.
I would take it as a glibc bug / lack of optimisation. At least definitely one where the fault lies in glibc given that your showed other libc as more optimized. And given that POSIX puts ":/etc/localtime" as implementation defined[1], I think we should avoid it, glibc isn't alone in dealing with timezones. 1: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
