If you do something like copy-on-write (for storage, and possibly for memory, too), it could be fairly light-weight.
Disclosure: I am working on XenServer.
Disclosure: I am working on XenServer.
With tasks queuing up as they already are, I might not be able to keep a fresh VM pre-warmed every time, either.
edit: The other factor is of course the prospective cost of a brand new configuration. Unless I find I can't prevent the current config from being breached and ephemeral VMs will fix it.
Ach, I see now what eru meant by copy-on-write VMs.
(At least as long as you have a general purpose operating system. A special paravirtualised would probably not need to make much of a difference between booting and resuming. But that's only a theoretical musing for your circumstances.)
This is my new plan of last resort if I can't prevent the current sandbox from failing.