I've no problem loading many more events than that using json, and
there shouldn't be any built-in limitation to the xml parser.
Churning through large xml files can be slow on browsers, so it helps
if your xml doesn't contain extraneous elements that aren't used by
your application of timeline.
I'd suggest looking at events in your file at the point where it bombs
out and see if there is any malformed xml in the file, or something
like a nonsense date.
--Mike