If you have a Hyper-V host machine with a lot of RAM, say 128 GB of RAM, then you should know that leaving the pagefile setting on the host to its default value of System Managed will cause a pagefile to be created that has a size equal to the amount of RAM in your system—in other words, your pagefile will be 128 GB in size! You don't need a pagefile anywhere near this large on a Hyper-V host machine—you only need a pagefile big enough to be able to get a kernel dump for troubleshooting purposes. Anything larger than that is a waste of the host's disk space. So instead of accepting the default System Managed pagefile setting, you should specify minimum and maximum pagefile sizes equal to 1x and 3x the amount of RAM used by the host operating system, respectively.
Mitch Tulloch is a Microsoft Most Valuable Professional (MVP) and widely recognized expert on Windows administration, deployment and virtualization. For more tips by Mitch you can follow him on Twitter or friend him on Facebook.