Dynamic memory: provide a maximum with virtual memory setting
You are able to set a maximum RAM value for the guest. When the guest needs more than that it will swap to it's own paging file.
When a guest is swapping to it's paging file, this gives a heavy disk load on the disk store where the vhdx is stored, causing all VMs on this store to slow down. It also causes problems with replication, as the pagefile is replicated too.
Add a Virtual memory amount that is added above the maximum RAM amount.
Hyper-V will then provide diskspace as RAM to the VM, but this diskspace can be located on another array, making sure that the array where the VMs are stored are not saturated by the swapping of the specific VM. And because it is RAM for the VM, this data wont be replicated.