Reboot into normal mode and observe for any changes in disk usage. It wouldn't harm disabling other third party (non Microsoft) services as well. Do this by booting into safe mode and disabling all avast services. OP, you could disable Avast temporarily to further investigate if it's the culprit instead of uninstalling. Spunk.funk, would you care to explain how Avast fares worse off than Windows Defender? I'd agree it being an integral part of Windows, it's been highly 'optimized' (read stripped down to bare bones functionality) hence is light on system resources, but it's nothing close to the efficiency and effectiveness offered by Avast, which is the leading free anti virus.
