As I understand it, a pagefile is only used to write out the contents of least recently used memory pages (blocks) when memory is getting full so that the current program can be fully in memory. You do not need a pagefile if your memory is nowhere near getting fully used because there will be nothing to write out.
Have you checked how much memory is actually being used? Open Resource Monitor and then open a heavy Cubase project and see what is being used.
64GB is a huge amount and is only likely to get anywhere being fully used if you are running samplers in memory resident mode rather than streaming from disk.
I would think that if a 20+GB pagefile is actually required, there might be so much distracting disk activity that DAW performance might be affected.
Note that if you want to upgrade Windows at some time, there will need to be at lease 20GB spare on the OS drive. Also, the \Windows\WinSxS folder 'fills up' over time as drivers and devices are installed but not reduced when they are uninstalled. Unfortunately, the size it shows is not real but because it is full of symbolic links to the locations of the real drivers, it only thinks that the folder contains so much. Basically, it can get the the point where the OS thinks that there is not enough room to run an update, even though there really is.
Therefore, with Windows, I would run an OS drive large enough to always have much more than 20GB spare.
FYI: There has been a lot of hype over the years about avoiding using SSDs for pagefiles because all the small writes would prematurely use up an SSD's write count limits. In actuality, MS's telemetry has shown that while there a lots of small reads from the pagefile, writes consist of a relately few 1MB blocks. In other words, the writes are saved up in a reserved-memory cache and written out as a large block. MS therefore recommends that SSDs make the perfect pagefile drives.
PatanjaliHalf of the folk music duo, DevaKnighT. Music available from CD Baby (MP3/FLAC) and the usual culprits. All recorded and processed on Cubase 7.x at 192k.Comp: i7-4930X : Asus P9X79-E WS : 32GB : ATI2460 : SSDx5 : UAD-2Q : Dell S2340Tx2 & 3008x2.
HW: Nmn U87 Ai : JA251x2 : YRG : Korg padKontrol+microKEY2 : RME FF400+800 : M-Patch-2 : Tannoy Reveal Active+TS-12.
SW: Win 8.1 Pro 64 : Cubase 7.5.10 64 : iC Pro : RX3Adv : Ozone5Adv : Goliath : SO Plat Pro : Pianos : Gypsy : Sup.Drum 2.0 : AT7.