Issue #19461 has been updated by catlee (Chris AtLee). I ran into this myself, and implemented a workaround here: https://github.com/ruby/ruby/pull/13968 The idea is to cache our offset from GMT, and then use that in subsequent localtime calculations. The cache is valid for every second within the same GMT minute. ---------------------------------------- Bug #19461: Time.local performance tanks in forked process (on macOS only?) https://bugs.ruby-lang.org/issues/19461#change-114379 * Author: ioquatix (Samuel Williams) * Status: Closed * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- The following program demonstrates a performance regression in forked child processes when invoking `Time.local`: ```ruby require 'benchmark' require 'time' def sir_local_alot result = Benchmark.measure do 10_000.times do tm = ::Time.local(2023) end end $stderr.puts result end sir_local_alot pid = fork do sir_local_alot end Process.wait(pid) ``` On Linux the performance is similar, but on macOS, the performance is over 100x worse on my M1 laptop. ---Files-------------------------------- localtime_test.c (1.28 KB) localtime_test.c (1.21 KB) clipboard-202302251716-rh6ma.png (234 KB) -- https://bugs.ruby-lang.org/