in my current environment, we have (nearly) all tables jorunaled and we are using commitment controll to get maximum throughput by paralellisation. We have some non transactional workload running without commitment controll (about 30 million inserts to one table with about 1000 million records) and we turn off journaling because journal management of os/400 is a nightmare (managing receivers by system from time to time fails with maximum parallelisation, - savact doesn't work anyway -) The performance impact is near zero (in words: no effect!!!). What helps a lot with this, is changing the maint of the indexes to *DLY and changing back to immed to force the rebuild in parallel. Other things that help for such operations is working with extracts to force selects over join and order operations to prevent the changing query engines from trying to slow jobs down by trying new optimizing strategies. I have switched on journaling for all files over the years in more than one environment and I never saw a performance breakdown as you are expecting!