We've been using Sophos AV SMB for over 10 years and have just had to uninstall it from a MacBook Air for the first time ever as it has been traced as the root cause of severely reducing battery life.
Every few seconds it was hitting the CPU with 99% usage and the fan was running far too frequently. We tried turning off auto update, scanning, and all other 'live' options, but it still continued. I have read elsewhere that v9.3.1 Cloud had a similar issue, which was reportedly fixed with v9.3.2 but the download for the Small Business Edition remains at v9.2.8
Having uninstalled Sophos the battery immediately reported an improvement of predicted battery life from 1.5 to 3.5 hours and the fan has stopped
Yosemite is at v10.10.5
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