I understand regarding images and caching, as I mentioned already.

In fact, the site I’m working on at this point has better optimized
images and about half the page size (2MB) and requests ( it’s nearly empty,
apart from part of the homepage) but using the Pingdom test, it’s
already quite slow at roughly 2.5-3s

So I worry what it would get if the whole site is finished.

There is some caching optimization that I can do here (not fully, since
some of the work and marketing images should get updated fairly regularly)
so I guess I’ll see how much that saves me.