I have been fighting this issue since we upgraded last November. We went from version 2.10.17 to 3.2.3. It was done as a fresh install (new directory tree) but on the same machine as the old version (Amazon instance running Debian 5.0.9. 2x Xeon 2Ghz CPUs, 2G of RAM)
I did diffs on all configuration files and transferred any non-default settings (there weren’t really any) from the old installation.
Since the upgrade, send times of our list of approximately 48,000 newsletters has gone from about 7 hrs to 13 hrs. I keep looking at the phplist settings since everything else is identical to the previous installation.
I found this thread:
I tried making the changes suggested in the thread but send times have not changed.
Any pointers for troubleshooting this issue would be appreciated.