Is separate insert / update more efficient than upsert?

[myukassign]

I have a continously growing table. I have to perform an insert update. Please suggest me which is the best approach.
1. Do update in Job 1, Then do insert in Job 2
2. Select Upsert mode and do it in one job.
Which is more efficient and faster? I am using Db2 stage. Will I face any perfomance hit by doing insert/udpate in one job.

[chulett]

Upsert is never 'more efficient' unless, perhaps, your mechanism to determine one from the other is highly inefficient.