Your vCPU per core ratio may not necessarily be too high. Do these VMs that are exceeding 10% have more than 2 vCPUs? A VM with 8 vCPUs having CPU ready of 10% is not bad. The threshold of CPU ready > 10% is generally based on a 1vCPU VM.
Are there any CPU limits configured on your VMs? That can contribute to higher CPU ready times.
Typical solutions are to remove unused vCPUs, remove limits, or add more hosts.
I agree with homerzzz on the typical solutions.
If you aren't sure what CPUReady is... it's basically the amount of time a VM has to wait for CPU(s) to be available.
If your host has 16 cores, think about a restaurant with 16 tables for one. Each time a 1 vCPU VM comes in, it gets seated at the first available table, completes it's task and then leaves. When a 4 vCPU VM comes in, it has to wait for 4 tables to be empty so it can be seated. While it's waiting, if a 1 vCPU VM comes in, it will get seated right away and not have to wait. This is why having multiple vCPU VMs isn't always a good thing and also why, when a user says a VM is slow, throwing another vCPU at it may make the problem worse, not better.
The chart you posted doesn't show a lot of detail. You may want to dig in further and look at what VMs have the high CPUready, how often it happens, for how LONG of a period is the ready value high, etc.
Good luck! Let us know how you make out.
