RE: [External] : Re: Smarter M-x that filters on major-mode

[Drew Adams]

> >> I'm worried about performance. IIRC I've seen 20000+
> >> commands upon M-x invocation...
> >
> > Even when you type some text to match?
> >
> > Perhaps you're using some completion framework
> > that starts displaying candidates without waiting
> > for any input to match?
> 
> Yes. It is equivalent to M-x <TAB> with the default
> completion system.
> 
> But even if you wait until you type the first character,
> the filtering could cause a perceptible lag.

There are ways to deal with that.
Option for minimal # of chars before trying to match.
Option for minimal time period before doing so.
Option for delay before rematching automatically
  (updating automatically)
Option for threshold for when such things kick in
  (e.g. fewer than N candidates => no delay)
...

None of this is complicated.  Such things are really
part of any UI that provides automatic matching and
rematching - or at least they should be.

Pretty much anything automatic needs to provide
"governors", to mitigate the behavior, especially
in extreme situations (e.g. zillions of whatevers).