Starting a new kitty process is quite slow. With --single-instance "new
invocations will instead create a new top-level window in the existing
kitty instance"[^1] to allow "kitty to share a single sprite cache on
the GPU"[^1], so that startup is almost instant.
For this to work best, launch one hidden "daemon" instance at startup so
that the kitty process is always running, even when no OS windows
exists.
[^1]: kitty(1)
Link: https://github.com/kovidgoyal/kitty/issues/330