EEVEE-Next recently got a Pixel Size feature can be used to increase performance while navigating, at the cost of reduced quality when updating the viewport, and reduced quality on some asset types when the viewport stops updated (a limitation at the moment that may be fixed in the future). You may want to checkout this setting to see if it helps you.
As for improving performance in general, developers are still working on it, and there are some features that may be added that could allow for settings tweaks that can improve performance (E.G. Adjusting the shadow resolution scale per light).