TIMA cpu use VS DLYJOB

We run a "never-ending" job that monitors for
shipments that are ready for customer delivery
and which require an EDI 856 Advance Shipment
Notice.

My question is why the amount of CPU use reported
on Work with Active Jobs shows something like 34%
when the job is in Status = TIMA ?

The exact percent CPU use appears to vary depending
on load so that the use during Status = TIMA is lower
on a busy system, and higher on a less busy system.

This job is based on an SQLRPGLE program that calls
sleep() between steps which process products as they
are prepared for customer delivery and creates the
required documents and data required for the Advance
Shipment Notice.

I wonder if it would be better to replace the call to sleep()
with a call to a CLLE module to run a DLYJOB command ?