So you are rending out 4K out at 1080 then and it wants 46 hours for a 5 hours video?
Yea I don't know how much a M.2 would help. If you think of it this way
900GB of files
SSD Read and write about 500 each if you average out all the brands
that is 1GB every two seconds
30GB every minute
and 1800GB an hour (This is theoretical max for sequential write)
It could move the amount of data you have in 30 minutes if the conditions were right and even with 4K each RAW file is what? anywhere from 5-50MB?