Yes, it does. How much longer depends on how much juice the computer is using to run. You have some control over this with your power management settings. Specifics vary with OS and release, but the default is generally to run everything full bore while plugged in. If you turn down the screen a bit, turn off wi-fi if you're not using it, slow down the processor if that's an option with your computer and it still performs acceptably, set the disk to spin down after use (depending on what you're doing; this can be counterproductive) and fiddle with whatever other parameters your software lets you modify, it will charge faster.