Jumpy autocomplete results

After fixing autocomplete not finding some users at all by making it perform the search, as a side effect the results change after the search has been done so many users have experienced it as being jumpy and unreliable (typically no one has actually filed an issue about it 😠 )

Ways to address this:

• seemingly obvious: just use search results only and not user store, wait for results before displaying, no jump. This is no good, I tried it, the search isn't good enough, it doesn't handle everything and especially not after the 2nd @ character. We don't want to lose that.
• keep what we have now, but don't show results until request has finished, removes the jump while keeping functionality the same. although from a lesson learned in the first method, no search should be performed after second @
• use some heuristics to keep wanted results on top no matter what, like if you follow them etc. might have unwanted side effects that result in you not finding what you want