allow intellisense to have a delay under 500ms

[TheBearodactyl]

Feature Request

C_Cpp.intelliSenseUpdateDelay should have a minimum of at most 50ms, 500 is much too restrictive. a default of 500ms makes sense, but not a minimum

[sean-mcmanus]

I think VS uses 1 second and has no setting to change it.

The minimum of 500ms is also enforced in the cpptools process.

There is a problem with lowering it too much -- if you're using a TU that takes many seconds to update, then when you type completions work if the characters aren't typed before an update is queued, so although users can enter multiple characters for a completion in < 500 ms, at 50ms, it becomes harder and could make it appear that completions are always delayed behind an IntelliSense update (which I think is a more important scenario than slightly faster error squiggles).

And the speed at which IntelliSense errors would be reported would only be at best 450ms faster and it's usually not that critical for IntelliSense errors to be appear 450ms sooner.

Having a lower setting would enable users to optin to that if they really want, but we were worried about users not understanding the completion problem they could start having.

[TheBearodactyl]

maybe there could be a warning that shows in the logs if it's set under 500 then?