It's All a Question of Cache (Score 2, Informative)

The Intel PXA250 has only 32K/32K of cache, which means that any real application will experience an extremely high cache miss rate. The memory bus is 16 or 32 bits, and has a maximum clock rate of 100 MHz. So, if you're running the maximum width bus at its maximum speed, you're likely to see an instruction dispatch rate of about 50~100 million ops/second. That's slow, and there's really nothing to be done short of adding much more cache.