We've been using the Nokia Lumia 710 on T-Mobile (see our review) for a few days now and one thing we found is the device is fast. Now by fast we of course mean on T-Mobile "4G' HSPA+ network, which we're seeing quick downloads but also there's something else--the OS itself seems zippier. On WP Bench, we get around 88 for a score, which is high but far below the Titan and Focus S.
Upon closer inspection we noticed the screen rotation from portrait to landscape is very rapid. So rapid that while driving we saw it quickly toggle between the two modes when taking a sharp turn. That tells us that this is either a very sensitive accelerometer with perhaps a lower delay in the transition effect.
When compared to the Lumia 800, Samsung Focus S, etc. the Lumia 710 will always beat them in switching between landscape and portrait. We actually really like this as it makes the OS and device feel even faster (it's very useful for messaging apps where you need the keyboard). Anyways, we thought it was neat and we hope the Lumia 900 features the same type of OS modification too.