When I was running the DB Audioware DB-L Mastering Limiter plug-in, it was on a Hewlett Packard Pavilion dv8000 lap top that had a 3.0 Ghz processor and 2 GB of RAM. I ran it in Cubase SX 2.0 and later in Cubase SX 3, and ran everything through a MOTU 896 HD audio interface. I don't ever recall having issues running this plug-in, as I only ever had a need to run one of them at a time within a session, as this is indeed a mastering plug-in. Even if you wanted to run a few instances of this plug-in within a session, I don't think that you'd have a problem as long as you have a pretty stable system to work with.
While inexpensive enough for most DAW owners to afford, I'm not sure that it is worth it for the DB Audioware DB-L Mastering Limiter. While it's an okay enough plug-in that is extremely cheap, I wouldn't recommend doing anything but quick mastering jobs with this. It won't give you any sort of instant mastering, which you shouldn't expect from any plug-in like this. However, I do think that it lacks the fullness that other mastering limiter plug-ins bring to the table like the Massey Plug-ins L2007, which in my opinion is the best bang for your buck that you can get. I guess it does depend on what kind of platform you have, as most users won't be able to run this plug-in anyway. While I guess I'd say that those interested should try the demo, I'd still recommend going with the Massey L2007 over this as it doesn't cost too much more and has a sound on another level.