waiting for log buffer??

I don't understand what is happening (not unusual) in a particular informix instance. ids 7.30.UC7, hpux 10.20 a data loading script is building an index on a temporary table; there are two temp dbspaces, the temp table was created 'with nolog', and the build is using multiple threads. at some point, other sessions, doing inserts and updates to unrelated tables, get a 'G' in the onstat -u first flag position; at this time, the index build session seems to be stuck in a critical section - it shows a 'X' in flag four for a period of time (minutes, not seconds) and the server is *not* in a ckp wait state The sessions stuck on 'G', waiting for a log buffer, do nothing until the index build completes, then continue merrily. The log buffers are 32k default. The instance is logging to /dev/nul. There are 8 log files of 500 MB each. KAIO is being used, 4 cpuvps If anyone could enlighten me as to what is happening, I would appreciate it. A cure would be warmly received as well. tia James