Personally I'd hard code the speed and duplex also.

Can you actually make a call over the BRI? Forget the config for the moment and use an interactive command to test. Turn on debug q931 and term mon (Or log con) then issue this command...isdn test call int b0/1/0 xxxxxxxxxxxxxxxxxxxx = the number you...

To clarify do you see the latency only when using ping or do you also experience it with application traffic.

You described it yourself. It's a bus. To expand a little it's a medium over which all the components of a device can communicate.

From the information provided it looks OK to me. But there are lots of possible caveats. What led you to check the switch cpu? Are you troubleshooting a problme?James