This would save on having to do the gravity calculations. Then, when people, armed with their knowledge of gravity, start looking in more places, the universe must pick a configuration and stick with it -- but at that point, all of their observations have the original problem of freeing up memory somewhere else in the form of higher entropy.

This is wrong (even assuming that previous coarse-grained observations don't matter). If you are changing the model by refining it, choosing one option of more detailed data arbitrarily, then this process on the world-model isn't reversible: you can't "un-choose" that arbitrary data and remain able to reconstruct it (unless the data is not arbitrary after all and only depends on the world model that is already there). As a result, no magical increase in entropy occurs, and no resources get saved: it's not an operation on the subsystems within the modeled world, it's an operation on the system of whole-world model within the world of modelers.

Also, consider the fact that ultimate laws can never be discovered, strictly speaking: there will always be uncertainty, and maybe there won't even be asymptotically certain candidates, only turtles always deeper and deeper.