I'm working on fixing some performance issues of a Drupal 6 site. Very new to Drupal, been figuring things out as I go, so please bear with me here.

My client has a rather busy site and uses Boost cache. On pages where Boost cache is applicable -- their home page, reviews pages, etc,... -- it works great. Pages are fast, load testing shows that they can take whatever's thrown at them. I just discovered that with Boost enabled, pages that are not eligible for its caching, such as pages with polls that need to pull from the DB each time, they are significantly slower to load then when Boost is disabled entirely.

For instance, here are the Loader.io results of a page in question. The instances where it completed successfully were with Boost disabled, instances where it failed were with Boost enabled. Ignore that 100% error rate test that's second from the top, MySQL actually crashed after the previous test and I forgot to restart it before running again.

Boost kills performance?

All I know for sure is that the errors are caused by MySQL. It appears that Boost adds database overhead, maybe it has to check for information about cached pages and then it has to do a second query to draw the page if it doesn't find the cached information? I'd love any insight anyone can provide!

Edit: Screenshot of Boost expiration settings

Boost expiration settings

  • Boost module is created by a performance Guru(mickeytown2). It however has a somewhat complex configuration that can lead to some problems on certain configurations. Check the boost settings page to make sure it does not clear every caches on a page write. It's difficult to guess the exact configuration but I think there has to be some configuration that caused it.
    – AKS
    May 17, 2014 at 22:40
  • Also, if your pages are interactive for anonymous users, I would not use Boost. Investigate why you needed boost in first place, and try to optimize the bottom first.
    – AKS
    May 17, 2014 at 22:42
  • It does clear certain caches on certain write or update operations. I'll update the question with a screenshot in case something jumps out at you. As for whether or not to use Boost, it does feel like the best way to do the majority of the site. There are only a few pages with interactive elements for anonymous users. I'm working on optimizing queries, that's how I discovered this issue in the first place! :-)
    – clg
    May 17, 2014 at 23:14
  • If you have access to the database, convert the boost_cache table to innodb. That should solve a lot of the issues you're seeing.
    – mikeytown2
    May 18, 2014 at 1:43
  • @mikeytown2 Did that, unfortunately didn't fix the issue. Same symptoms. Anything else I should check out?
    – clg
    May 18, 2014 at 6:05

1 Answer 1


There is an option in boost that let you count the number of hits even of cached pages. That version hits your database on each page hit. It's fairly small, but it still loads all the modules as it has to go through the standard Drupal initialization.

Make sure you turn that off if it is on to ease the load on the DB.

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