There are actually 3 tweets. Of course, the timeline has changed but in terms of confirming that they will make a performance version, these tweets are pretty convincing. Tesla doesn't want to talk about the performance version right now because they want to sell more Model S cars. I guess the anti-selling will continue until they reach 5,000/week Model 3 production at the end of Q2 2018.
Elon confirms performance with ludicrous (tweeted on 29 Apr 2016)
Twitter
Performance version mid-2018 (tweeted on 24 Mar 2017)
Twitter
Model 3 Performance in mid-2018 (tweeted on 29 Jul 2017)
Twitter