Adding and removing resources from vCMP.
I want to remove cores from a vCMP and assign it to another one. Will removing cores from a vCMP impact it? Same for adding operation as well.
Easy part first - adding resources will very likely NOT have a negative impact. The worst thing I can see happening is having some strange behavior on traffic distribution and persistance due to CMP (https://support.f5.com/csp/article/K14358). This can be more evident if the amount of traffic is relatively low.
Now, if you remove resources, I'm going to say it depends. Less resources mean less capacity to process traffic, so you should be quite sure that your current resources are more than enough, by a good factor, before advancing. Try to check your performance statistics for at least a week, or whatever time you think is representative. If CPU and RAM are always at 10% or less, I'd say you can safely go to half your current resources.
Also, when removing resources, be wary of vCMP guests with only 1 vCPU. I make it a point of never using those for production environments, even in low traffic conditions.