I reported freezes on the newsgroup here : http://article.gmane.org/gmane.comp.lib.sdl/34324

console.log contains :
"2007-08-18 08:48:22.368 Tennis Elbow 2006[277] Exception raised during posting
of notification. Ignored. exception: *** -[NSLayoutManager
glyphRangeForTextContainer:]: given container does not appear in the list of
containers for this NSLayoutManager."

someone said he had the same trouble but with SDL 1.3 and pointed out this revision :
http://libsdl.org/cgi/viewvc.cgi?view=rev&revision=3217

Then, I commented out these lines :
1- [field_edit interpretKeyEvents:[NSArray arrayWithObject:event]];
2- field_edit =  [[NSTextView alloc] initWithFrame:r];

and now, the freezes seem to be gone ! (at least on my system, I still need to get confirmation from my users).