Need suggestion, thin or oci driver

HI all.

on the backend system, they use Oracle RAC as a database system.

last week, we used thin driver to connect to this RAC system. but, we got issue on the connection. the error:

The Network Adapter could not establish the connection

i have a conclusion, that issue come from thin driver. To support TAF on RAC, driver connection must use Oci driver.

two days ago, i changed driver to OCI driver. The connection issue not found till now.
But, we find the bigger problem on our WM system.
the first. Oci driver is more slower than thin driver (thin without RAC. Directly to one Oracle system).
the second. When the available thread less then 8%, oci library kill our WM process (i got from the oracle forum, that oci can kill java process).

how do we solve issue??

thank You.

Jakaria Ritonga.
Telkom Indonesia