> it is still a valid measurement if the frameworks don't enable persistent connections by default
I don't agree. Frameworks often prefer the "safe" option over "performance" by default. If you activate persistent connections by raw coding it [1] then you should also set an absolutely obvious database configuration flag like [2] in a framework.
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[1] https://github.com/TechEmpower/FrameworkBenchmarks/blob/mast...
[2] https://github.com/TechEmpower/FrameworkBenchmarks/blob/mast...