1 - I have tested with some devices and the swipe feature (even slowly) seems to work properly.
Can you send us more details about your problem?
2 - Yes, there is an internal timer, you can see how it works in PDFView class vOnTimer(Object obj) void
I can reproduce the problem with a "medium" PDF with an Asus Transformer TF101 (presumibly a slowly device compared with new one).
I have a menu with a PDF list. Immediately after my choice (I open the PDF) I try to swipe as fast as I can (I think I could swipe faster after the open but before than open finish), and the activity seems freezed.
If I wait just a little after the choice I cannot reproduce the problem.
I can't see the timer, in the java source I cannot find it. In what file I can see the timer implemented?
I use the 2.9.11b
I have a standard license, so only a question: it's right to see invalidate called continously even without user interaction? If it's normal, no problem... If not I have to see implementation to stop unwanted works.