If you have a performance issue it's notthe mega menu causing it. Much of the code including the portion you mentioned are from the core autonav block. I've got 7 menus on my demo page on c5extras.com and it loads super fast.

I'd suggest you try adding the autonav block and see if there's any performance difference or turn on caching.

Trust me, it is that function. Take that out and all is well.

Standard autonav code is one thing, a massive recursive sorting function is another.

You don't have many items in your navs.

This package has been used on hundreds and hundreds of websites and no one else has mentioned any performance issues. The recursive function from the Autonav block would have been used on hundreds of thousands of sites, and with no complaints in the forums about that. That recursive function in Autonav has been exactly the same for as long as I've used C5.

If you take it out and it works fine, then leave it like that. The only possible way you could have performance issues is if you're showing hundred of pages in the mega menu, which would just go against common sense anyway.

A few questions that will help to get a resolution for you:
* What version of C5 are you running?
* Do you have caching turned on?
* What type of server are you using (Linux/Windows)?
* Who is your hosting provider?