JavaScript timeout on iPad Safari vs. Win 7 Safari

I am using the latest version of jqGrid (4.x) for an application displaying local data.

1. Win7: All works fine on several browsers (Chrome, FF, IE, Safari).
2. In iPad's Safari the grid works excellent, but there is one issue:

When I unload the grid because I need to redefine its columns, this either takes extremely long or times out. I am using purely local objects - 开发者_开发技巧no back-end connectivity involved. Debug console on iPad Safari: JavaScript execution exceeded timeout

I have tried both ways:

 $("#myGrid").GridUnload();
 $("#myGrid").GridUnload("#myGrid");

I can reproduce the issue, when I skip the GridUnload part the issue is gone. As said above, on a Win7 Safari this is not problem at all.

Any ideas how I could work around the issue?

-- UPDATE ---

This issue was very hard to trace for me, since I am not aware of how to debug JS code on an iPad. So far, this issue seems not to be specific to jqGrid, but the timeout happens whenever something in JS takes to long. For some reasons I do not understand yet, this seems to be the GridUnload().

Can somebody tell me, whenever this Safari iPad Javascript timeout is happening, I have no idea what triggers it.