using oracle materialized view with one hour refresh interval to reduce high concurrency
If your oracle DB is at a very high concurrency and you find that the top sqls are some views, then there's a quick way to resolve this: using oracle materialized view. You may consider setting the refresh interval to one hour which means the view will refresh every hour. After the setting go live, you'll find the normal performance will appear.
For more information about oracle materialized view, you can visit http://en.wikipedia.org/wiki/Materialized_view
Here's a image with high oracle concurrency: