With the release of Zenoss 3.0.2 likely to be the last in the 3.0.x series, it is useful to have a page to list any bug fixes or performance tweaks that may be applied until the next release.  Please feel free to add anything you may have, linking to patches, forum and wiki posts documenting the fixes.

• Upgrade to Zenoss 3.0.2 if you're not already running it.  It contains a number of performance enhancements in additional bug fixes.
• Zenoss 3.0.3-tagged tickets: these are tickets flagged to be fixed if there is a 3.0.3 release.  If they are in the state "Patched" then there is a patch that may be applied with zenpatch.
• Internal ticket #2623 "Querying the catalog with 13,701 devices pegs the CPU": 'zenpatch 22685' for the fixes. Poor Infrastructure tab performance 3.0.2 is the thread describing it.
• Also from Poor Infrastructure tab performance 3.0.2, increase your ZODB cache size (which is different from your ZEO cache size). First, go to http://SERVER:8080/zport/global_catalog/manage_catalogView and get the number of records in your global catalog. You can use this as a rough estimate for the size your object cache should be. Next, round that number up to the nearest 100,000. Finally, go to $ZENHOME/etc/zope.conf and find this:

  <zodb_db main>
      ...
      cache-size xxxx
      <zeo.../>
  </zodb_db main>

  Set that cache-size parameter to your rounded-up number (no commas, of course). Save, then restart Zope (zopectl restart). You should notice a significant improvement.

• Performance Tuning for Zenoss Storage is an excellent source of enhancements for Zenoss storage performance.
• How to tweak zenoss needs to be revisited to determine which fixes are still applicable.
• You can enable RRD caching with the patches from question regarding: Products/ZenRRD/RRDUtil.py
• While unsupported by Zenoss, Distributed Collectors and Collector Tool ZenPacks can be used to do distributed collectors for additional scaling with Zenoss 3.0.