A 512 node IBM Scalable POWERParallel Systems SP2 was installed at the Cornell Theory Center in October 1994. During the past couple of months we have been porting and optimizing code for carrying out lattice QCD calculations. Present performance is far from ideal, however, and optimization efforts are still under way. The rate limiting step in our code involves a rather generic inversion of a large, sparse system, based on a partial differential equation in a multidimensional space. The insights we have gained so far may be useful in diagnosing performance in a wide class of applications.