This question is a bit generic - as it can apply to any EEPROMs - like the ones in iPhones - etc, not just Arduino, but the question is regarding the wear phenomenon that happens with it as with all other non-volatile memory - with the actual performance/speed.
If I understand correctly - the general thing that happens is when EEPROMs are write/erased after many cycles - the oxide gate begins to deteriorate - rendering more and more parts of the EEPROM unusable.
My question in particular is regarding the read performance of the EEPROM. From what I read so far - even if the oxide gate slowly meteorites - as long as its still "readable", the read performance is NOT affected at all throughout the life of the EEPROM.
Basically from this - it is why people generally don't think of performance issues reading their EEPROM when updating they constantly update the EEPROM NOR firmware in their computer BIOS or iPhone or other devices - because that whole issue is irrelevant.
Correct me if I'm wrong guys...