I have 32GB in my laptop and the sim never uses more than 16GB of it (usually closer to 14GB), so I’m really not sure you would see a benefit with more than 32GB.
Windows flies with multitasking with so much headroom to run in despite FS running simultaneously (I’m GPU bound not CPU bound). I think from what others report VRAM use is limited /restricted by the sim beyond a certain point too, although mine is usually between 40-80% of the 4GB VRAM in use at any given time.
Like someone has pointed out previously a lot of RAM and VRAM memory use/utilisation has been shrunk to let FS run on XBox and was implemented post SU5 (FS XBox release)