VIM Freezes on OmniComplete with a PHP file?

I'm trying to check out omnicompletion. I created a php file

then when I type in "subs" then CTL+x CTL+o I expect to see a pop up of su开发者_运维百科bstr. However it just freezes and I have to force quit it. I've tried it in MacVim and regular VIM, same result. I wiped out all my plugins and started new and it still happens. Any ideas?

I should also note I've tried https://github.com/Shougo/neocomplcache which worked for a while and now as soon as I type one letter in it starts to freeze on me.

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The PHP omnicompletion script launches a small window showing a "prototype" of the method highlighted in the context menu. It's possible that some autocommand tries to do too much at window creation or lost of focus.