I agree 100% with the OP.
Everything he stated is happening on my 830 and on my girlfriends 830, went back to the store and checked the 830's on display. They all had it!.
Some people keep defending they're 830 and i can relate to that, but comon people, this phone is not optimized as should be and IS doing everything the OP said! Compare it to an 820 and you will see, do you guys not see the same i see? U have magic phones? wtf
The jagged scrolling is the biggest issue in my opinion! I hate it. coming from a 820 that is what the eye catches the most. this screen is horrible, oversensitive or whatever i really don't know, but it's not the windows phone experience i was used to and hoping for when i purchased this phone!