Intermittent Performance Problem - What does oninit do?

We have Informix V7.30 running on a SCO-Unix box. Several times during the day, the response of the system goes in the tank. At these times, sar indicates that there is 0% idle time. Our DB has around 2.5 million rows across about 30 tables. There is another SCO-Unix box on the network with another Informix DB, and we use synonyms to facilitate table reads across the network. I don't have a good tool to view the running processes, so I use ps -ef to create an output file of the processes, wait several seconds, and then do another ps -ef to a different output file. Using diff on the two files, always indicates that oninit is the process getting the most time. This seems to have gotten worse over time, e.g. this wasn't a problem a year or two ago, so I don't know if it's indicative of a problem related to the growing size of the DB, or some tweaking I need to do. I do Update Statistics on a regular basis, but this doesn't seem to help. When oninit isn't gobbling up CPU time, the performance is excellent. Again, this seems to happen during the day, unrelated to user activity. What is oninit and what could it be doing? Does it do different things at different times? Could this be a poorly timed DB administration task that is executing? As a side question, does anyone know of a good system monitoring tool I can use for SCO? I've used top on HP-UX, but that doesn't exist on my SCO boxes. Any help would be greatly appreciated. Joel