iOS 7 Safari: OS locks up for 4 seconds when clicking/focusing on a HTML input

Question

UPDATE: The issue seems to stem from having many select elements on a page. How random is that?

So here\'s the issue. On iOS 7 Safari, when tapping

Answer 1

We had the same or a similar problem at my company. Whenever we displayed a large number of drop down lists and then a user clicked on a drop down, IOS 7 would freeze the page for a minute or two. After it unfroze, everything would work properly from that point forward.

This affected all input types. The large number of drop downs were actually hidden on first load - the user would initiate the display of the drop downs. Until the drop downs were displayed - everything would work fine. As soon as they were displayed, the next input click, even an input that had been working properly, now would cause the browser to freeze.

As others have noted, it seems that IOS 7 has a problem when parsing the visible inputs in the DOM after the user first interacts with an input. When the number and/or complexity of the elements/options/DOM are higher, the freeze is more pronounced.

Because it always froze on the initial user interaction, we decided to initiate a hidden user action as soon as we displayed the list of drop downs. We created a transparent button (it could not be hidden - it had to be "displayed") and initiated a click on it as soon as the user opened the drop down list. We thought that this would make IOS start parsing the DOM quicker, but found that it actually fixed the problem completely.