Hi,
last 4-5 months we experienced the issue with "group repeat" on Kobo and Ona, they use your code, so I think the problem is here. Tested in different browsers, even MS IE lol.
After 15 iterations of group repeat, every next opened with progressive delay, 25, 45, 90, 200 sec an so on. Just frozen page, scroll doesn't work.
The issue doesn't relay to complexity of group, the group with only one question has the same problem.
I tried to ask help of Kobo or Ona team but still no success. Guys, I don't want to use another tool like form.com or any other for my surveys! I like ODK, but that is really problem for users.
ODK tools are described and documented at http://docs.opendatakit.org/. Do you use any of the Kobo/Ona variants of those? If so, please let us know which and we can try to help.
You're talking about browsers so my guess is that you're using Enketo which is a fantastic, compatible tool. If that's the case, you probably want to take a look at the help channels there. My experience has been that it does struggle with large forms and you may want to try ODK Collect if that's an option.
This is all free, open source software! ODK Collect is an alternative you can use with hundreds of repeats. If that doesn’t work for you, consider contributing code or funding.