Re: 1020 Dual Core vs. 1520 Quad Core...
Does anyone have a sense of whether the Preview runs faster on the Quad Core-chipped phone? My 1020 is certainly slower. I don't think I am surprised. But, I expected that - kind of - and wonder if anyone has installed on both phones and can comment.
I haven't been able to compare with a quad core device, but I have a 1020 and do not find mine to be "slower". What I have noticed was that when it was first updated, for the first few hours / days, it was still syncing content and loading information. This caused a poor battery life initially, and made it seem terrible. My brother noticed the same thing with his 920, and friend with her 928. All of us noticed improvement by day 3 at the latest.
I also noticed that if you set a background image for your live tiles, there will be a noticeable lag when going back to the start screen. This can be alleviated by disabling the background image, but I don't find it to be a problem, just noticeable.
Of course, the last thing I noticed (and is discussed everywhere here) is that the Music, Videos, and Games apps are just awful. They take forever to load, they cause sluggish behavior, have lead to reboots, and are just all around bad. Wait for updates on those.