Re: customize-apropos-options takes forever...

[Richard Stallman]

    Emacs 22 has a lot more options, of course, and more faces and buttons and
    such, but it still feels like things are less efficient now. In emacs -Q,
    there are 4698 lines in the buffer in Emacs 22; in Emacs 20, there are 2333
    lines (about half). But Emacs 22 takes *far* longer than twice as long.

Probably something really is wrong.  The question is what.

Would you like to try running Emacs 22 under a debugger
and stopping it a few times uring this operation?
If you notice a place that shows up frequently in the backtrace,
that might be the place that is using the time.