I concur entirely. Not only is the 8255 going to be too slow, but a lot of other devices you might want to use with your ~1 CPI device are going to be a problem as well, assuming you wish to operate at more than a few MHz. When working with high speed microcontrollers, you really do have to pay attention to the timing. Even things like address latches can be an issue; a 74LS573 is usually out of the question, whereas a device like a 74ABT573 can typically deliver the level of performance required.

CPLDs can be a nice alternative for I/O expansion among other things. However, I should mention that in my experience, at least with the XC9500-series devices, unreliable/erratic operation seems to result when you connect the CPLD to noisy, low slew rate inputs. Proper signal conditioning is a necessity.

You might also want to look into I²C or other serial I/O expanders. Assuming the performance is sufficient, these can provide a simple interface to a large number of devices with less effort than a CPLD-based design.

--Sasha Jevtic