Hi Tom I'm honestly not sure about anything. =) I use the exact same flags as with 8.4 for the dump:
${BINARY_PATH}/pg_dump --host=localhost --user=postgres --no-password --blobs --format=custom --verbose --file=${pg_dump_filename}_${database}.backup ${database} So unless the default behaviour have changed in 9.x I'd say I don't use compression. I will try to force it to no compression and see if it's different. Sadly the instruments session stopped recording when I logged out of the system yesterday. Doh. =/ Cheers -- Henrik Cednert cto | compositor Filmlance International mobile [ + 46 (0)704 71 89 54 ] skype [ cednert ] On 21 Nov 2017, at 22:01, Tom Lane <t...@sss.pgh.pa.us<mailto:t...@sss.pgh.pa.us>> wrote: "Henrik Cednert (Filmlance)" <henrik.cedn...@filmlance.se<mailto:henrik.cedn...@filmlance.se>> writes: I'm not sure if I can attach screenshots here. Trying, screenshot from instruments after running for a few mins. It looks like practically all of pg_dump's time is going into deflate(), ie zlib. I don't find that terribly surprising in itself, but it offers no explanation for why you'd see a slowdown --- zlib isn't even our code, nor has it been under active development for a long time, so presumably 8.4 and 9.5 would have used the same version. Perhaps you were doing the 8.4 dump without compression enabled? regards, tom lane