The performance that you can expect when running OS/2 Warp Server Advanced on OS/2 Warp 4 is similar to the performance of running OS/2 Warp Server Advanced on a single processor machine.
Of course, the performance compared to OS/2 Warp Server SMP on a multiprocessor machine is much lower, because this operating system has been optimized to typical server use and multiprocessors.
If you need a very efficient server with the maximum performance possible (for example if you run a server application like Lotus Notes on it), we strongly recommend using OS/2 Warp Server SMP.