🚀 go-pugleaf

The sleep seems to be a (broken) variation of an idea I posted long ago.
Unfortunately, the code you posted is clearly wrong.  The right way
to do it is, after the read returns, if it returned short, to sleep.
The code posted unconditionally sleeps before trying the first read.

Measurements showed that at 1200 baud it cut way down on system load
(and this really makes a difference - a uucico at 1200 baud only adds
about .2 to our load average instead of 1 like it used to) with almost
no effect on throughput rates, but at 9600 baud it hurts throughput
drastically (since 1 second is far too long to sleep at 9600 baud)
and is a bad idea.  At 4800 it's a close call, and a local decision
should be made.