I have an app that needs to update a large amount of data over a large number of entries. Basically it does some 7,000 inserts and/or updates but it takes a looooong time (l
What you suggest is correct. Try reducing the amount of queries you send to the server since this will save you from the multiple communication overhead.
Of course, if the inital select ranged query returns too many data, then you may have a bottleneck on PHP.