The Programmable Logic Data Book contains one set of timing parameters.
Are these times valid over the entire range of Recommended Operating Conditions
and Temperature range and is there any difference in the timing if Vccio is
connected to 3.3V instead of 5V?
Yes, the AC Characteristics and the Internal Timing Parameters listed for all
XC9500 family devices are valid over the entire range of Recommended Operating
Conditions and Temperature range. These are worst case values, therefore the
time given will correspond to when the device is run at the maximum rated
temperature and minimum rated Vccint
The difference between using 5V and 3.3V Vccio is negligible and both are
covered with the same internal timing parameters in the datasheet.