Given the example of Twitter I&#x27;d say that the answer to the second question is yes. They rewrote the Ruby (not Rails) backend and continued serving tweets. Did they have theirs hairs on fire? Maybe, but I don&#x27;t think you&#x27;re never in hurry when you rewrite parts of a popular service.<p>About question number one: no idea, but you can add more machines and scale horizontally. Then you might ask if you want more efficient code between the web server and the database. You can optimize up to C. Finally, Twitter is still using Rails for the front end AFAIK, so it shouldn&#x27;t be so bad.