This is pretty interesting. I have some questions.
Since I don't know the product, I don't understand why doing all of this data crunching on the frontend. Seems like the same motivation could be applied to moving more of the heavy work to the backend before sending results to the frontend. Making the app more of a thin client. Am I missing something, is there a reason to keeping the work on FE?
Cost. To take it to an extreme, you could render everything on the back end and stream video, like GeForce Now or Stadia, but in doing so, the backend needs to be quite beefy. As clients these days usually have some modicum of processing power, doing it on the front end so you're not also playing for an extra fleet of VMs on the backend saves money and increases revenue. At a high level, you want the line for revenue to have a higher slope than the line for costs. Not a huge deal from 0-1 customers or 1-10, but does become an issue at scale.
That doesn't seem to be the case here - they already mentioned that the data is heavy, which means they have to send a huge amount of data over the network, only to crunch it down and show a subset of it (I don't think the UI shows all of that data at once). This seems more costly than sending some UI updates over the wire, for example.
Since I don't know the product, I don't understand why doing all of this data crunching on the frontend. Seems like the same motivation could be applied to moving more of the heavy work to the backend before sending results to the frontend. Making the app more of a thin client. Am I missing something, is there a reason to keeping the work on FE?