This was the proximate cause of #2579.
#2582 is a deeper fix, but this will remain
as a footgun, so may as well fix it too.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
Package mono provides a fast monotonic time.
Its primary advantage is that it is fast:
It is approximately twice as fast as time.Now.
This is because time.Now uses two clock calls,
one for wall time and one for monotonic time.
We ask for the current time 4-6 times per network packet.
At ~50ns per call to time.Now, that's enough to show
up in CPU profiles.
Package mono is a first step towards addressing that.
It is designed to be a near drop-in replacement for package time.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
