ArcSDE (10.2) Database connection is so slow on Oracle 11g

Question

I create a enterprise geodatabase on oracle 11g by Enable Enterprise Geodatabase tool (From arcgis desctop 10.2). Everything works fine but connection is so slow. Only difference is , Oracle database is under IT dep control and other applications also using same database. There are so many users and tables. Their all tables are granted as public. So when i connected to database from Arc Catalog i can see the all that hundreds of table from all users. I don't know this can be reason of this slow problem. Because we test all network connection speeds are normal. 
I have another oracle database with same specifications on a simple workstation (version 10.1), but database has only my sde users and tables. That one is so fast working.
Any one has some idea what is my problem?

VinceAngelo · Answer

Above and beyond the "worst practice" issue of PUBLIC grants, the existing system
is likely burdened by all the other users accessing those hundreds of tables.  Using
a database for GIS is a significant load on a RDBMS; if the system is older or under-
powered then there's little chance for performance on par with the dev system.

- V

Musa_SerkanArslan · Answer

Thank you for reply.
Unfortunately our customer request us to create geodatabase on their existing system. Initially i could not guess this problem. I try to push them to do some thing.
Still i am open for any other solution.

MarcoBoeringa · Answer

Everything works fine but connection is so slow...Their all tables are granted as public. So when i connected to database from Arc Catalog i can see the all that hundreds of table from all users. I don't know this can be reason of this slow problem...
Any one has some idea what is my problem?

It most likely is the problem...

Granting access rights, even if it is read-only, to all tables in what most likely is a non-geodatabase enabled enterprise database, certainly isn't best practice.

Your solution therefore is to create database roles in Oracle, and associate the database roles with appropriate read/write access to particular tables as necessary in your GIS workflows, and assign your individual GIS users (yourself) or even better (Windows) user groups to the appropriate database roles to limit access to spurious tables.