I'm betting you're a "tech guy", so the I suspect the following non-answer will resonate - Based on the details you've given in your question, there's really no good way to answer it. Your question is a bit too broad.
The community needs to know things like the hardware you're running. The Tableau workload you're dealing with, what your reports look like in terms of complexity, whether you use extracts or not, and so forth.
That said, have you read through the Tableau Server help topics on performance? They offer a good start.
Also, I personally would move off of 7 to 8.1 - it is more performant.