SoapUI Pro 3.5.1 or 3.6 PermGen Space Error

Hi,
We are facing PermGen Space Error problems while executing the complete projects. As per SOAP UI's recomendation, we have

1. Enabled Discard OK Results at Test Case level.
2. Enabled Errors only options (Logs only Errors at TestCase Logs)
3. Increased Java Memory max upto 1024 and Added MaxPerm to 256 in batch file.
4. We have also added start up script= Logger.getRootLogger().setLevel(Level.FATAL) at the project level

But none of these solves our problem.
Our services are complex and we have written highly complex script assertions for it.

Looking forward to hear other options from you.

Regards,
Kiran