-(As previously mentioned in a comment i made) unrendering echoes out of your FOV, and adding a transition effect for the light that echoes emit (from being on to turning off); for when it stops being rendered.

-Checkable box in the TAB menu (or somewhere else) to stop showing (rendering) echoes you have already read before (have opened and looked directly at for a determined amount of seconds).

-Checkable box in the TAB menu (or somewhere else) to stop showing (rendering) lighting emited by echoes, when they are at a far distance (either determined by the user, or a pre-set number).

If anyone would like to give more ideas, that would be cool1!!1!