Facebook's iOS app has some nice features but it's painfully, neck-stiffening slow. It won't be for long though. The NY Times reports that next month, Facebook will release an update that'll completely overhaul the app to make it blazing fast.
Why has the Facebook app been so slow? Because the current version of the app is nothing more than a web browser inside an Objective-C shell. Stuff is being constantly pulled from the web, hence the lag time. The next Facebook app will replace all that sluggish sludge by using more Objective-C, which in turn would use more of the iPhone's hardware and as the Times puts it, "building most of the functionality directly into the application so it has to collect less information from the Web."