VST Plug-Ins And Virtual Instruments

There are two basic kinds of VST plug-ins. Those that are hardware accelerated, like UA and TC-Electronic offerings. Similar to the Pro-Tools TDM, they don't use the native processor in your PC or Mac. This saves horsepower there, and leaves more of that for the other plug-ins you use that are native-based best vst. But, you're limited by how much power the hardware PCI cards (or remote boxes they offer) will provide. They offer varying levels of power/price, and are usually expandable, and they are very powerful, so this usually isn't going to be a problem.