Yesterday evening we did the following:
Turned off the VM's and restarted the host. In Bios we checked the power setting for the CPU, this was not set to performance, we changed this to performance setting. This morging (till now, 14:30 pm) the average cpu ready is back to "normal" 1% to 1,5%, a lot better then yesterday. Also no permorance issues today.
Could a CPU power setting have this big impact in this case? Didn't experience this before, even with servers with CPU power setting not set to performance.