Oracle Database Discussions

We have done a number of 11g upgrades recently and are seeing a recurring theme - connecting to remote DBs from an 11g source (hence, acting as can 11g client), are slow. The issue first manifested itself to us as slow response across DB links, but we now see it in multiple aspects. As an example, I have a server with both a 10g and 11g installation on it. Running tnsping from each of these environments to a common target DB show drastically different results. Given that everything else is the same, the only difference being the Oracle version, it seems to me it has to be an 11g-specific issue or behavioral change.

when running the tnsping from the 10g environment, response time is 100 msec
when running the tnsping from the 11g environment, response time is 1430 msec

I can recreate the issue using SQL*Plus to connect to the remote DB.

connecting from the 10g environment takes approximately 1 second
connecting from the 11g environment takes approximately 4 seconds

The target DB is 11.2.0.3.2.

Has anyone else encountered this? I have an SR open with support, they are directing me to Network/SysAdmin, and we are planning some traces.
But if this were DNS or network related, it would seem to me the issue would exist in both 10g and 11g - we only see issues when 11g is the source/client.

Thanks.