IQ works best for loading and deleting as bulk operations. Even updates are best set up as a bulk delete followed by a bulk insert
When you load without the bulk loader you are invoking row-by-row inserts. This is most likely causing a version build-up in your user dbspace. To reduce this, you can set up commits to occur more often (commit after every 'n' rows).
This is still inefficient and slow.
Unless there is a reason (e.g. concurrency), stick to bulk loads or enable the RLV dbspace and set the table in question for RLV. This will still be slow but will allow the row-by-row inserts to work.
You will still have to size accordingly and ensure the complete transaction for the load fits into the RLV cache memory (or use commits after every 'n' rows to help reduce the memory requirement).
Chris