I'm following the discussion from its start.

The performance related with the hardware and the server configuration is not the big problem after you get the matters settled on. Adding faster HW resources won't help you much. And based on your analysis the environment is far from maxed-out utilized.

I think the time for the code optimisation had come there. With efficient code (t-sql, EF, Linq, ...) you can do wanders. That's what I've learned and experienced in the past several years. However, it's a long process, .. which requires staff and expertise.