Comment if you can: We've got an app that is pretty slow. Partially the fault of the front-end doing a lot of synchronous promises. But on the backend we have

Comment if you can: We've got an app that is pretty slow. Partially the fault of the front-end doing a lot of synchronous promises. But on the backend we have a lot of calls where we are getting a list off foos from the DB, then spinning through for loops and making one or two synchronous calls to other microseconds to fill in the details. I hated algorithms - but this is O(n^2) and we could cut it down to 2n -> O(n) by spinning off the fir loop to futures. This is java using completable futures with whatever thread pool the generic executor creates. Any issues?