I experienced the same exact symptoms when using an Xperia M2. The lag was so worrying, for obvious reasons, that I have just switched over to an iphoneSE, and am very glad that I did! Another problem you may experience with the Sony is that the app continues to use a lot of power and data, even when 'closed' it was able to flatten my battery in only 4/5 hours! There is a solution to the battery drain, which is to 'force quit' the background app using the power usage dialogue in settings. I'd advise sticking to your iPhone! [emoji12]