It would be nice if osisoft would get some benchmark to evaluate and report the latest pi afsdk against different pi data archive and after versions, at least the latest release.
These reports should answer most of the questions of pi afsdk developers in terms of performance, stability, diagnostics and release improvements.
A discussion around what kind of dataflows are relevant in the benchmark would help, don't you think?
Generalized metrics are often difficult to compare with a specific case as there are a multitude of factors (memory, network latency, data density, I/O speed, concurrent applications etc.) that can affect the performance of an application.
However with AF 2.9+ you should be able to generate metrics for your environment and use this as benchmark to verify performance improvements on code changes/upgrades.
Using metrics in your AF SDK code
For a discussion on Serial/Parallel/Bulk calls for data retrieval using AF SDK refer to KB01216 - AF SDK Performance: Serial vs. Parallel vs. Bulk