ARM DS slow connection to Fast Model

Hello

on the same Linux RH7 machine, it happens that the performances of ARM DS when connecting the debugger to a waiting Virtual Platform  Fast Model (using CADI)  are very random, and often, it takes 3-4 mns to 

establish the connection. Sometimes, it takes only a few seconds.But most of the time, it's too slow.

I don't understand why there can be so much difference in performances of connection to a virtual platform. What can I do when ARM DS takes too much time to connect to a Virtual Platform ?

Best regards

Frederic Huguet