Combination of your new phone, updated cell towers and your DSL connection, etc. Just like in the old days, when TV switched to broadcasts "in living color" and you still had a black and white TV, you still only got a black and white picture since that is all it could produce. When you got your color TV, then you got both color and black and white broadcasts. Same with your phone, the slowest link is what regulates the speed of sending a photo. Cell phones were originally for conversations which use very little bandwidth. Sending photos takes much more bandwidth, etc. to send it over the signal, so even though your cell towers may have been updated, your old phone took much longer to send the photo since it was most likely the slowest link in the chain.