ViewPager setCurrentItem freezes UI thread

Is your adapter handling very large amounts of items? (very large > ~2²⁰ items)

ViewPager.populate(int) will loop from the current item position to N, which is the number of items in the adapter - so if you've set it to something large (such as Integer.MAX_VALUE) this will takes some time, but will eventually finish.

If this is your case, search for "endless pager" related questions, such as Endless ViewPager android, or limit the number of items to something that's reasonable for the main thread.