The first releases of the Oracle Management Pack did not manage the number of sessions used on an Oracle database all that well. As can be seen in the Oracle Enterprise Manager screenshot below (peak 1 and 2 on the graph), the OPSLOGIX user opens many sessions and causes a rather high CPU and CPU Wait time.
With the performance improvements made in version 184.108.40.206 of the Oracle Management Pack, the performance overhead for monitoring the Oracle database has been dramatically reduced. The screenshot below shows the performance of the old Management Pack in peak 3. Peak 4 shows the initial upgrade of the Oracle from the previous version to version 220.127.116.11. Peak 5 shows the normal performance footprint when operating normally. Also notice that there are now only three OPSLOGIX sessions active.