In contrast to this question about running Bitcoind in a low-memory environment, I have an opposite use-case.

I want to run a bitcoind full node (no wallet) on a Linux server with lots of memory but not particularly fast disks. What are the maximum useful memory constraints (dbcache=, maxmempool= and total amount of page cache) that you can give to bitcoind to maximize its performance? That is, at which point does giving more memory to bitcoind start yielding diminished returns?