George, definitely wrong. Only with the VFP mtdll are you sharing the VFP runtime among all instances of the server. So, you could have 100 threads and there would only ever be 1 copy of the vfp runtime in memory. In my experience, Apartment model threading is a very efficient and fast way to service multiple threads - it's just not as effcient as .NET's model(mostly because of the thread-switching of the apartment model). But, not many people are ever likely to see the difference.
You may be describing running vfp EXEs in a pool or something which actually is very inefficient since you actually are loading up everything with each copy. Many of the older 3rd party web tools are built on this technology, mostly because they began before vfp mtdll technology was introduced.