unfortunately the latest* Firefox 18 is using way too much cpu, about 20% compared to <5% for Firefox 17.
This is Firefox idling. Logging into Zimbra and waiting for it to settle takes some time with CPU usage up to 100%.
Can somebody else confirm this?
Hence recommend not to update to Firefox 18 if using the Zimbra Web Client.
Note: the percentages are for the Firefox process only (in my case that is /usr/lib/firefox/firefox).
Release 7.2.0_GA_2669.UBUNTU10_64 UBUNTU10_64 FOSS edition, Patch 7.2.0_P1.
*latest on Ubuntu 10.4.