The HTC Titan is a beast. Its 4.7-inch display gives Windows Phone a canvas that is nearly tablet-like, and the 1.5GHz Snapdragon processor driving the device makes one of the world's smoothest operating system even smoother. In the two weeks I have been carrying the Titan, I have yet to see a crash or lag. I can't even say that about Apple's iOS.
Animations flutter around on the Titan and native apps open into a usable state in the blink of an eye. The user interface is unbelievably smooth, and the UI "sticks" to one's finger during navigation just as well as iOS. Scrolling in apps is lag-free, though inertial scrolling is still a bit off. When the user releases a finger following a flick, the scroll seems to accelerate at the same rate regardless of how hard the user flicks. It's awkward, but hardly a major problem.
My biggest performance-related issue is the amount of time it takes most apps to refresh with new data. On AT&T's HSPA network, data speeds are fast and latency is quite low. I regularly saw download speeds of between 2Mbps and 4Mbps during my tests in and around New York City, and upload speeds hovered between 1Mbps and 1.5Mbps while connected to HSPA. Still, it can take 5, 6 or even 10 seconds or more for an app to refresh with even the smallest amount of new data. I haven't pinpointed the culprit yet -- different developers tell me different things, though everyone I've spoken with recognizes the issue -- but I suspect that it's often a combination of the OS and developers' inexperience with coding apps for it.
Beyond that, I can't stress enough how much I'm enjoying Mango. The "tombstoning" feature, akin to application state-saving in iOS, is implemented quite well, and apps that take advantage of it load from the background almost instantly.
