Linenumbers Performance

[slisson]

The line numbers extension significantly slows down the update of the editor. Maybe we can make the computation asynchronous and reduce the delay of the main editor.
I think it's not critical that they are always up-to-date. They can be out of sync with the main editor for a short duration.

[alexanderpann]

The events are already throttled, but for some reason the line numbers panel gets hundreds of events per second to tell it that an update has to happen.