bug#2445: 23.0.90; file name completion GCs a lot

    It may be, indeed.  But there's no good reason why it should be much
    slower in such a circumstance.  A factor of 2 slowdown should be
    expected, but not much more than that since the "xmail/foox" pattern
    doesn't offer much opportunity for partial completion.
    So it sounds more like an implementation inefficiency somewhere.

If you can speed it up, that would be a fine solution to this bug
report.  But otherwise I think the feature should be disabled.