I'm currently running Pro Tools LE 8 on a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run Pro Tools LE 8 with a Digidesign 002R audio interface or a Micro Box if I'm on the go. I always run Digidesign DigiRack Ping-Pong Delay and other delay plug-ins on auxiliary tracks to save processing power, but either way this plug-in doesn't take up much processing power anyway. I generally use other delay plug-ins before this one, so I haven't exactly maxed it out to it's full potential, but since all Pro Tools users have this already, all you need to do is simply try it out for yourself to see how well it runs within your system.
For a free plug-in, the Digidesign DigiRack Ping-Pong Delay actually has a pretty clean sound quality. It isn't the warmest or fullest sounding delay plug-in out there by a long shot, but for a freebee it is certainly more than adequate. You can definitley get some really cool ping-pong tones without having to mess around too much with it, so in this sense it's nice to have some quick and easy ping-pong delay. I'd definitely encourage all Pro Tools users out there to give this plug-in a whirl...