Method list filter is crazy slow

[mraleph]

Reported by @rsturgell

Looking at a list of ~2000 compiles, it can take multiple seconds per keypress to filter the methods! That should be instant - must be something funny going on here.

[mraleph]

I will look into this first time next slice of work. I think what happens here is: a) we are firing change event for every added character (should use delay instead) b) when filtering by sources we use inefficient split-line source representation.

Additional burden might be coming from the list rendering itself as it is done by Polymer. Previously I was hand rendering DOM for this list as it was slow to render is using declarative data binding. Have to profile and see if it again the case.