Right now I'm sharing 81.8 TB and 554.648 files and fopnu is using 5.6 GB of memory. I would like to be able to use other programs aside from fopnu, so what can I do to reduce the used memory? Should I share less files?

I removed some shared folders but the memory remained the same. Then I restarted the program and it went down to 670 MB. I'll have to rehash everything again now.

that is not very high for ram with all those files.
i use close to 2gb ram for over 8tb of files.
and of course you are going to have to re-hash any folders you removed and then re-added.
in the settings-files you can turn up your hashing.

"in the settings-files you can turn up your hashing."

As in the number of threads to use or the % of CPU utilization?