Frequent Server timeout

Hi, I am using the WP Poll as a simple multi choice quiz. Basically I have a simple page with something like 20 polls in different div. A javascript take cares to hide and show the div sequentially. Now I’ve noticed that everything works fine as long as I have only one voter per time, but with three or more users answering the quiz at the same time, I’m experiencing a very frequent “server time out” as soon as the press the vote button. Also it happens only on iOS devices. Apparently android and desktop devices have no problem. I don’t know how to troubleshoot this item. My hosting provider claims that there’s no issue on the server side. What can I do?