This is not a surprise as the phone was 3 years old and so much slower then the 3G model.

For owners of the nearly three-year-old original iPhone, it looks like iPhone OS 3.1.x will be the end of the line in terms of official OS updates. Jobs didn’t explain why Apple is no longer going to offer software updates for the original iPhone, though we suspect it’s part of a plan to phase out the product line.

[mashable.com...]