MULTIPROCESSOR Flag and poor CPU Allocation

We are running Informix 7.11 UC1 on an HP9000 with HP/UX 9.04 operating system. This is a 2 CPU machine. The Informix CPU configuration originally looked like this: MULTIPROCESSOR 0 # 0 for single-processor, 1 formulti-processor NUMCPUVPS 1 # Number of user (cpu) vps SINGLE_CPU_VP 1 # If non-zero, limit number of cpu vps toone Per the recommendation of a consultant we turned on the MULTIPROCESSOR flag. So now our configuration looks like this: MULTIPROCESSOR 1 # 0 for single-processor, 1 formulti-processor NUMCPUVPS 1 # Number of user (cpu) vps SINGLE_CPU_VP 1 # If non-zero, limit number of cpu vps toone Since we made that change, we have had a problem with some medium to heavy-duty sql statements that appear to be using practically all of the one CPU that Informix is using. Thus, all other Informix processes (including our On-Line systems) are getting very little CPU and performance goes down the toilet. Could the change in the MULTIPROCESSOR flag have caused the performance problem or is this just my imagination?