I have about the same system as you. With a bit of management, it’s still capable of a lot.
I rarely encounter problems, but occasionally plug ins cause lag, stuttering and so on, usually older 32 bit bridged ones. These seem to be more and more dodgy with each successive version of Cubase. In my C8.5 which I keep for compatibility purposes, they all work faultlessly.
If it is such a thing, it can be hard to pin down in a big project, so I disable all VSTis and if that clears it, re-introduce them one by one. Similarly with FX plugs, disable each, at the plug in GUI (not bypass on the mixer which leaves the plug ins active) systematically until you find a culprit. Once I pin the offender down, I freeze it or find an alternative.
Of course it may be that the problem is elsewhere, but it’s good to eliminate as many things as you can.
The other thing that has caused these me issues is graphics software, I have more than once had to roll back to older versions, staying well behind the beta releases.