Nope, appsync came out a long time after we were in production and while it's very powerful, it's would require a full rewrite of our application. It's an application service/framework upon itself.
The Bustle stack looks like Redis/Elasticsearch => NodeJS Lambda GraphQL API layer => (sometimes api gateway) => NodeJS lambda render layer => api gateway => CDN. We're working towards removing all the api gateway usage if possible with smarter CDNs like cloudflare workers and Lambda at edge, but it's not currently possible.
This setup gets us an average of 70ms api response time and less than 200ms worst case rendering time. Higher than 90% of cache misses never gets the worst case as we can serve stale content in those cases. Lots of room for improvement too. =)
I'm curious on what's missing from Cloudflare Workers to allow you to remove the API Gateway usage. We're actively looking for more advanced use cases so we can make sure we prioritize upcoming features. Reply here or send me an email at <username> at cloudflare.com.
