Is all the CPU being utilized ?

Is all the CPU being utilized?

If the kernel utilization is over 40%, then investigate the operating system for
network transfers, paging, swapping, or process thrashing. Otherwise, move onto
CPU utilization in user space. Check to see if there are any non-database jobs
consuming CPU on the system limiting the amount of shared CPU resources, such
as backups, file transforms, print queues, and so on. After determining that the
database is using most of the CPU, investigate the top SQL by CPU utilization.
These statements form the basis of all future analysis. Check the SQL and the
transactions submitting the SQL for optimal execution. Oracle provides CPU
statistics in V$SQL and V$SQLSTATS.

you have serialization and unscalable behavior within the server. Get
the WAIT_EVENTS statistics from the server, and determine the biggest serialization point.