I'm having a problem where my ppp connection stalls (meaning I don't have
any packets coming or going) whenever my CPU load becomes moderately high.

For example, if I'm running rsync I see packets coming and going in kppp
like crazy, but if I run a game, tops reports my CPU load at 30% and the
packets suddenly die. Quitting the game causes the packets to come back
almost instantly (unless I waited to long...)

I use a serial hardware modem (US Robotics 56K Ext Fax modem). I have crtcts
enabled in ppp/options, and I tried the other flow control (crtdts) w/o any
improvement. I also tried shutting off all compression (nobsdcomp,
nodeflate, novj, etc..) thinking that would lessen dependence on the CPU.
It didn't help.

FYI I have AMD 64 3400+, slamd64-10.1 distro, kernel, pppd version

Any ideas?