AD7893-2 +5V Power Rail

The AD7893-2 converter has a specification on the bottom of the second page of the datasheet giving a Vdd of 5V, and under comments says "+/-5% for specified performance." 

I am curious what performance degrades when the part is ran outside these limits?  I am looking at running this part at 5V +/-10%.  Will there be a degradation in accuracy of the ADC, speed, both, or something else?

Any information you have on what will degrade with rails outside those limits and any quantification of this degradation would be helpful.