Hi,
I did more investigation on the COPY performance on Windows.
By using community distributed binaries, the COPY performance of PG16.6 and PG17.0 is worse than PG16.4.
However, by using the binaries build by myself, there are no difference.
So, it is not the problem about the source code after PG16.4.
On the other hand, I noticed that 82a4edabd2 is degrading COPY performance on Windows.
I will write the detail in the next e-mail.
Regards,
Ryohei Takahashi