Thanks for your response.
My laptop has 4GB only, but I expect to run several of VMs on it. Generally, I disable all unused services in any Linux install. In this case, I will not use zfs and HA so I doubt they will change Proxmox behaviour for me if disabled. I'm also hoping to disable whatever writes to the disk every few seconds even when all servers are completely idle.
Any help to achieve the above is most welcome.