Slow Audio/Video on i3 iMac and ESU1808 audio interface

Question

Symptoms (with both 32bit and 64bit kernels):
Everything runs as expected at 96 kHz for a while and then one of the following occurs:
1) Everything slows down, so audio sounds deep and MIDI triggers are slow. In Renoise, movement through the pattern slows down accordingly, and in DVD Player the video frame progression also slows accordingly. At this point I can fix the sound by changing the sample rate (in Renoise using the preferences and in DVD Player by using Audio MIDI Setup) to another frequency and then back again. Then the same issue occurs again after a while.
2) Sound stops and there is a short burst of noise coming from the speakers at regular intervals every 1 or 2 seconds. Pattern progression in Renoise also slows as with issue 1, plus the level meters within Renoise freeze and change in time with the noise bursts. In the ESU1808 control panel, bursts come up on the meters, including on the inputs. On the front of the unit, the MIDI Out light flashes in time with the noise bursts. Here the unit must be switched off and back on to correct.
The same occurs in Cubase LE 4.
Running the unit at 88.2 kHz has caused the second issue, and running at 44.1 kHz and 48 kHz is fine.

Answer 1

Not quite Chris - your hospital will probably have a device or several devices distributing IP addresses connecting everyone to the network - the DHCP server. That device could have more work to do (ie number of users, traffic volume) than it is capable of delivering at speed. Using Bonjour for iChat relies on this device matching up buddies - if the device is busy you'll have to wait longer to be matched up for video chat. Ask your IT department to look at whether these devices are hitting 100% CPU - if yes that will most certainly be your problem waiting 5 minutes to connect.
Meanwhile - a separate suggestion - it sometimes helps to speed things up by reducing the number of directories your Mac looks at when searching busy networks. AppleTalk is the original Bonjour - SMB relates to communication with Windows. If performance remains unchanged simply tick them back on.
Any use?