The RAM disk is intended for special case scenarios (embedded devices, WinPE) when writeable disk is needed but difficult / expensive to provide.
It's not going to improve your system performance. If anything it will degrade it as it is nowhere near as efficient as the Windows cache manager.
It depends on how much RAM you have. If you have say 2TB of RAM, it should make things faster, although copying the file system to it and then doing redirection might be an issue.
Could antivirus APIs be used in a program to detect changes to the disk while it copies things to the RAM drive? Could a junction point be used afterward to do redirection? When you want to shut down the system, could the changes be merged back into the
filesystem without causing problems as it is done? These questions probably need to be answered before doing this kind of thing.