PHP eAccelerator change for low volume sites

One of the options we offer to speed up busy PHP sites is called eAccelerator. However, eAccelerator doesn’t usually help for low volume sites, so we’ve disabled it by default in those cases. The rest of this post explains more.

eAccelerator

When enabled, eAccelerator creates extra “cached” copies of PHP files that can speed up PHP if the same scripts are run often. However, eAccelerator also has some slight drawbacks: it uses extra memory, adds a little overhead when creating the cached files, and slightly increases the possibility of incompatibilities. For a site that doesn’t run the same script at least dozens of times every hour, these drawbacks probably outweigh the gains, and we’ve been trying to track what the “break even” point is.

We’ve reached the conclusion that eAccelerator helps on sites that use more than 7 “CPU seconds” per hour (aka “0.2 CPU units”), but not on sites that use less than that.

As a result, we’ve disabled eAccelerator by default for those low volume sites. This will not result in any noticeable change — but in the unlikely event one of our customers wants to override this for some reason, you can do so in the PHP Settings section of our control panel.