The following bug has been logged online:
Bug reference: 3714
Logged by: Radim Kolar
Email address: kolar(dot)radim(at)gmail(dot)com
PostgreSQL version: 8.3 beta2
Operating system: BSD/64bit
Description: applications using COPY are now much slower
Details:
Applications using COPY for batch insert few records are now much slower on
heavily updated table than in 8.2.
Using COPY for importing database dumps in 8.3 is noticeable faster than in
8.2
I recommend to add some configuration file switch for switching COPY between
old and new mode or add COPY NOLOG keyword.