Forget hyper-optimizing, how about we just stop throwing away gigabytes for no reward? If we get there, then we can start thinking about maybe actually optimizing anything
browser tabs are the perfect examples, period. These things were being done with native widget toolkits twenty years go. Or going back even further, TUI forms. Rich text with straightforward inline graphics is nice, but we're paying an extremely heavy price for it.
Personally I might not even mind so much about the memory except the latency from the garbage collection, swapping, etc absolutely kills interactive performance. My TI-85 had a snappier interactive experience than my "modern" phone.
I think a large part of the problem, at least on the embedded side, is that people really just don't have standards for these things should feel. When I tried out the first gen Nest in a store, my first thought was it was a joke and who would actually buy it with 100ms+ jittery UI lag. But lo and behold, people did.