GTK3 on Windows takes a long time to start up (in update_keymap)
gtk_init function takes around 600 ms to execute, adding to a noticeable lag when starting up a GTK3 application. Almost all of this 600 ms is spent inside
update_keymap in gdk/win23/gdkkeys-win32.c.
Worthy of note is that I currently have 4 keyboard layouts active due to the work I did previously. Glancing at it, the runtime of
update_keymap appears to be linear in the number of keyboard layouts, so if you only have one – most common case – it's probably not as noticeable. But I think even 150 ms is a lot.