recursive algorithm. On which side is it better to implement it?

Question

PHP

Task:
Select data recursively from an external resource and present it in a more convenient form for work.

Question:
How to proceed? Is the server configured to do this, while the number of requests to the resource can be up to 4000 (respectively, a long time) or is it implemented on the client side using js libraries?

Answer 1

Select on the server and cache.

Answer 2

I am for server implementation. Only the "recursive algorithm" confuses me. Better in line.
- frontend (communicates with the client, if necessary, informs about the progress of work via SSE / WS)
- queue (for tasks, exchange of goals)
- backend (parallelize work)
- storage (storage of results + report)
and caching, of course.

Answer 3

If there is not much data, then it is easier and more convenient to do everything on the client (build the menu in the form of a tree, show small data). But if the data for recursion is large, then it will really be easier to work on it once and cache the result.