The folks over at Modsupplier.com have uploaded a video demonstrating the speed of PSJailbreak on loading a game, running it, and switching.
To quote:
In this video we demonstrate the speed of your original games loading from the internal HDD using the PS Jailbreak and the backup manager software, the video shows loading up a game already saved on your hard drive, the speed that it loads and then some gameplay footage. Then we show how to exit a game and select the next one you wish to play, we then also show some in game footage of the second game and once again how to drop back to the main menu when finished.