Memory usage in WordPress 2.7, 2.8 and 2.9 Beta 1

After suffering from a few RAM issues lately here at, I decided to do a comparison with previous WordPress versions to see if there was anything particularly wrong with the latest development version of WordPress.

The latest dev. version of WordPress (currently heading towards 2.9 Beta 2) is what uses. With it, the 32MB of memory available to the site were often not enough to do a plugin upgrade. Each time, to get the upgrade to finish successfully, I had to deactivate either one of the five active plugins, or the translation (I use to test the Greek L10n of WordPress).

What the comparison showed:

The numbers

I tried each of WordPress 2.7, 2.8, and 2.9 Beta 1 with and without the Greek translation and with three different themes: Default, Simplish, and Thematic. In each case only one (1) plugin was active: WP Memory Usage. The numbers in parentheses show the memory usage when the translation was active.

Default Simplish Thematic
WP2.7 17.26MB (19.95MB) 17.16MB (19.83MB) 18.01MB (20.87MB)
WP2.8 23.07MB (28.53MB) 22.97MB (28.43MB) 24.00MB (29.63MB)
WP2.9b1 20.17MB (25.64MB) 20.12MB (25.54ΜΒ) 21.08MB (26.70ΜΒ)

Environment info


  • Linux 2.6.18
  • CentOS 5 64bit
  • Apache 2.2.13
  • PHP 5.2.11
  • MySQL 5.0.81


  • WordPress 2.9 beta 1 (r12290 from trunk)
  • WordPress 2.8 (r11552 from trunk)
  • WordPress 2.7 (r10188 from trunk)
  • Default theme 2.9 beta 1 (r12290 from trunk)
  • Simplish theme 2.2.2
  • Thematic theme 0.9.6 β 06 (r571 from trunk)
  • Greek L10n 2.9 beta 1 98% complete (r10450 from trunk)


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The RAM numbers are from the WP Memory Usage plugin by Alex Rabe:

Method and other notes

For this comparison I downgraded via SVN from the latest WordPress trunk (r12290) to WordPress 2.8, then to WordPress 2.7. Then I upgraded again to WordPress 2.8 and finally to the latest trunk (r12290).

I repeated these four steps twice; that is, two runs in total. The numbers in the table are the averages. (MB values varied from 0.00 to 0.09 between the two runs.)

After each downgrade/upgrade WordPress asked me to “upgrade” the database. Interestingly, all eight database “upgrades” went OK and everytime everything seemed to work OK down to WordPress 2.7 (including the themes Simplish and Thematic, which were at their very latest versions, and also a few plugins I tried).

Quick conclusion

See the table! :-) Also, 64bit operating systems eat a lot of memory – but we already knew that. :-D