You should be able to deploy your app locally, access it via a logging proxy, (say mitmproxy), and observe the logged HTTP traffic to identify what's going on. Pay attention to HTTP cache mechanisms.
Rinse and repeat until you are less than baseline (and if you don't/can't, is SSR really a good tradeoff for your use-case?).
Once you have verified your app behaves itself it's time to repeat on the cloud platform and address the public setup.