Hello,
I am currently dealing with the following problem: We recently moved our Enterprise deployment to new servers and upgraded to 11.5. Since then, requesting attachments via the REST endpoint of a feature service (e.g. layers/0/features/401/attachments/1) consistently takes around 5 seconds, regardless of the attachment size, which is much slower compared to before. This only applies to the services that reference a postgresql sde, not hosted feature layers. The delay also occurs when I bypass the web adaptor and query via the arcgis server machine directly. Uploading attachments also seems to suffer from the same delay. ArcGIS Server logs the request as taking only a few hundredths or tenths of a second, including the database query, as I would expect, but then it takes ~5 more seconds for the server to actually send the response.

The server runs on Windows Server 2025. I already tried disabling defender temporarily, but no success.
Hope someone can help, thanks in advance.