My memory is that early VLC was actually a bit slower than MPC, at least on my low-powered Windows 98 PC of the time (cobbled together for schoolwork from spare parts). There would be skipping or a loss of sync between audio and video on some heavier clips that didn't happen on MPC.

But what I primarily remember in making the switch was that VLC could play everything I threw at it, right out of the box, without installing a bunch of sketchy codec packs. And that also allowed me to basically just throw the VLC binary onto my flash-drive, and then be able to open any videos as needed from parents'/friends'/school computer by just plugging in the usb stick. It was definitely a game-changer.