> Without setting TZ during normal operations yields approximately: 14,925 calls to stat over a 30 second period (or roughly 497 stats per second).
> With TZ set during the same time period results in 8 calls to stat over a 30 second period.
This is interesting but what would be even more interesting is what that means to wall time. My gut feeling is probably not that much.
Syscalls can be heavier than expected. One example is when an application is run inside gVisor. Another example is when a lot of eBPF code is attached. A third example is when a program is run under strace.
Disclaimer: I'm working on ClickHouse[1], and it is used by thousands of companies in unimaginable environments. It has to work in every possible condition... That's why we set the TZ variable at startup and also embed the timezones into the binary. And we don't use the glibc functions for timezone operations because they are astonishingly slow.