oncheck -cI with IDS 7.30.UC3-1 on AIX 4.21

Over the weekend we upgraded an Informix instance from IDS 7.24.UC1 to IDS 7.30.UC3-1. The conversion instructions recommend running update statistics and data integrity checks after the server isstarted on the new software. The Update statistics ran fine. Most oncheck commands ran with no problems. However, the "oncheck -cI <database-name>" command seems to run forever. It is performing millions of physical I/Os against our larger tables. In fact, it appears to be performing at least one physical I/O for each row entry in each index. When I cancelled the "oncheck -cI <database>" with an onmode -z <ses-id> command, the UNIX process terminated. But the Informix session continues for several hours until all indexes for the current (1,000,000+ row) table were checked. Has anyone else seen this behavior or have suggestions on how to run consistency checks in a reasonable time frame under IDS 7.30.UC3-1?