Some migrating their iOS projects over to Xcode 5 but not converting their project’s xib(s) or storyboard(s) might notice that the performance of Xcode drops when trying to edit those files. Looking in Activity Viewer, it isn’t Xcode that is taking-up all the cycles, but a tool, Interface Builder Cocoa Touch, that has now gone from using its normal smidgen percentage of CPU to over 60%! This will make editing a storyboard or xib very painful.
A search of “Interface Builder Cocoa Touch” will not result in links that address this is issue. After all, Xcode 5 has only been publicly available since today. So what to do?
The problem is the Interface Builder Document settings for the iPhone Storyboard or xib in which the performance is laggy.
Start by looking in the File Inspector of each storyboard in which the performance problem exists. It is likely that the storyboard Interface Builder Document setting was set for “Xcode 4.6”. That is, as it turns-out, bad. Changing the IB Default Document setting of the xib or storyboard to “Default Xcode 5” will fix the problem. Once you make that change, the Interface Builder Cocoa Touch tool will return to its sipping of only a few threads and using 0.0% of the CPU.