On kubuntu 14.04 updated daily, when the owncloud-client is not working (the client says everything is synced - green icon) there are two task that fo hours use 100% CPU.
When there is a sync activity (the owncloud client says he is syncing and the progress bar increases) the two tasks didn't excede 40%
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ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: KDE
DistroRelease: Ubuntu 14.04
InstallationDate: Installed on 2014-03-01 (78 days ago)
InstallationMedia: Kubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140227)
NonfreeKernelModules: nvidia
Package: owncloud-client 1.5.0+dfsg-4ubuntu1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
Tags: third-party-packages trusty
Uname: Linux 3.13.0-24-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip libvirtd lpadmin plugdev sambashare sudo
_MarkForUpload: True
apport information