I really like the idea of making startup faster but I would rather fix it at the source rather than adding another layer of caching. Virtual desktop and explorer initialization is already enough of a mess as it is.
Fwiw while looking at https://gitlab.winehq.org/wine/wine/-/merge_requests/5057 I believe I found some things that cause unnecessary refreshes of the display device cache during virtual desktop activation. The https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/win32u/winstation.c#L... line specifically should probably be changed to FALSE (force).