RL can extract games from 7z, zip or rar files when you start a game. So you can compress your games even if an emulator don’t support these file formats. And no there is absolutely no loss in performance. It just adds at game start some loading time for you to wait until it’s decompressed. It even deletes the temporary extracted files when you quit the game.
It also features a customizable fade in and fade out when you start or exit a game, has a pretty decent bezel support for all emulators, features automatically ISO mount and de-mount with Deamon Tools and supports individual xpadder profiles for single games or whole platforms.
Furthermore it has a feature called HyperPause. With HP you can pause every emulator even if the emulator doesn’t support it by itself and within the pause menu you can view manuals, guides, etc.
Some frontends like HyperSpin need RocketLauncher to work properly. So when former HyperSpin users switch to LaunchBox it’s just more comfortable for them to use their already set up RL then configure everything again in LaunchBox.