I'm jealous because you are not having to run NetWorker on Windows platform. Not fair!
Anyway, as for the performance in 7.5.1, I cannot say that it is better than 7.5 or 7.4.x versions of NMC.
Eariler I mentioned that some admins like to TS onto the NW server. I am considering removing the GST server from the NW server, and installing on a Storage Node that is less utilised, and forcing them not to log into the NW server.
However, can you explain whether you are using the NMC installed on your personal desktop, as that will send lots of info to/ from the GST database. Or are you using the NMC on a remote system, closer to the GST database.
I'm not sure if it the current version of NMC, but occasionally the NMC freezes and does not update - close and restart required. Case open with support, but they do not consider this high importance, so not expecting to be fixed soon. I have a copy of the latest NW 18.104.22.168 cumulative fix, which has a few pertinent fixes for our environment. It will take ~ a month to get through our internal process to put into production.