Problem with shell

Hi,
I connect to node via ssh, type login and password, but server responds with a huge delay. Shell works with awful freeze or doesn't work at all, while VMs and OpenVZ containers work properly. It's important to note that server respond normally when I try to send some command from remote server via ssh. After reboot server shell works good, but for 24 hours. Then this problem gets back....
I have this problem with server in Proxmox cluster and with standalone server Proxmox VE as well.

Configuration
Proxmox VE 3.4.6, 3.4.8, 3.4.9 (I didn't have this problem with previous Proxmox versions)
HP ProLiant DL380pGen8

any advice?
Thanks