Hi,
I'm using a VC with 2 EX4500 and the CPU is very good. My Junos version is 11.4R5.7
In your case, please try something below:
- Verify VC mode, if it's in mixed mode, try to change to non mixed mode
- Try to upgrade to latest Junos version, the recommended version now is Junos 12.3R12 for EX4500
Thank you.