For all the various APIs exposed by Salesforce like Bulk, Composite etc. each have their own developer guides which include like how to use them, and various limits applicable to them.
But I didn't find any published response time benchmarks. For eg: in Bulk API, if Insert operation is performed for Contact object, for an batch size of XXXX (with say XX fields) what is the average/least time taken for batch to complete.
Help out if I have missed discovering the right documentation.