I think the comparison to Firebase is a bit disingenuous. Their core offering is real-time synchronization of large, arbitrary data structures. From perusing Baqend briefly, it seems like your architecture is much more poll-based.
Baqend has streaming queries whose results stay up-to-date over time; purely push-based, no pulling involved. You just have to register your query as streaming query and receive relevant events or the updated result every time anything of interest is happening. In our opinion, this is not only comparable, but goes beyond the synchronization feature of Firebase, because our real-time queries can be pretty complex. A Baqend streaming query can look something like this: SELECT * FROM table WHERE forename LIKE 'Joh%' AND age > 23 ORDER BY surname, job DESC
We are going to publish this feature during the next weeks. But you can already read the API docs here to get a feeling for the expressiveness of the feature: https://www.baqend.com/guide/#streaming-queries
We also do have some benchmarks comparing real-time performance, which are under submission at a scientific conference, so we cannot share them yet.
Unfortunately, testing against Firebase using established benchmarks such as YCSB is not very useful, as it's unclear which limits are enforced on purpose and which limits are inherent to the database design. Would you be open to providing a Firebase setup for heavy load testing w.r.t. to throughput, latency and consistency?
For any readers, the test AFAICT is time to last byte for a single reader. It's a bit unfortunate that it seems local caching is affecting the bagend result by the time you switch the comparison to Firebase (though in full disclosure, Firebase's local cache isn't available on JS so that's a bit on us too).
I could give a few perf tips on the data layout for Firebase but it isn't clear whether the toy app has intentional indirection to model something more real.