I've never had any problems running the Bomb Factory Tel-Ray Variable Delay. I am currently running the plug-in on a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I use the plug-in in Pro Tools Le 7.4 that runs off of a Digi 002R audio interface. I have also run the plug-in on a Pro Tools HD system. While I always use a reverb or delay in tandem with an auxilary channel to save processing power, even if you didn't do this I think that you could run a few of these at a time if you'd like.
While the process of installing and using the Bomb Factory Tel-Ray Variable Delay is easy, for me it doesn't really matter because the plug-in doesn't have a good sound. Every time I have tried using this plug-in I find that it takes away more than it will add and it seems that it always kills whatever signal I run to it. While it will of course add a delay sound as advertised, the sound always ends up sounding less full and a bit dead after you run it through this plug-in. It can get a variety of sounds because of all of the different parameters, but it doesn't really matter to me because I don't like the sounds that it can produce. The price is reasonable and all that, but the sound quality just isn't up to snuff.