For 99% of the SaaS teams, low latency becomes an issue later unless the product itself needs to be catering with that feature. Focus with kits like this is to get everything running on day 0.
If your app goes viral for some reason and has to scale within hours its not easy to rebuild for performance in that timeframe. Then if u use stuff like AWS and your app has a shit payment model that allows free tier users to just waste resources, good luck paying off that invoice.