So i have a 640xl and I've really liked it but I've noticed a number of the apps I use run a lot slower than on my other phones, a galaxy note and an iPhone. Before anything else I'm very well aware that there is a large difference in hardware. To be honest I prefer the Lumia but it gets stuck on the shelf because of the slowdown in the apps. Here's my question is there a noticeable difference in app performance on the higher end windows phones? Or is it a problem with the apps themselves? I really want to buy a new phone but I'm on the fence. Thanks for the input.