Once everything the game needs is in RAM, storage is no longer a factor in the performance equation. For games that aren't open world, loading usually takes care of everything the game needs to play that instance. However, even for open world games like say GTAV, I've noticed that the game only asks for the bare minimum to be playable, then loads in the rest as needed. That is, it loads the boundaries of the map (so the physics knows how to work), then low res assets, then high res assets. Basically, it may not matter as much in performance than in the days of old that seemed to try to load everything at once.
If we're talking about online gaming performance, at a certain point it doesn't matter. The netcode and logic are sampling everyone's inputs at a fixed rate and this can be as low as the bare minimum FPS people are willing to play at, not to mention some games employ lag compensation. Granted, the in-game performance should be well above this sample rate (maybe like 2x), but the advantage of going further rapidly diminishes.