[all variants] High sshd CPU usage during sftp transfers

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http://ubuntuforums.org – I'm running Xubuntu 12.04 x64 on an AMD 64 X2 4200 dual core 2.2GHz machine. I'm connecting to it via SFTP from my Windows machine over my 100mbps LAN, using FileZilla. I noticed that when I transfer large files, sshd consumes a lot of CPU time: 1 transfer: Pegs one of my CPU cores at 100% and I only get around 80mbps transfer speed. 2 transfers: Two sshd processes running at ~60% CPU usage each, and my transfer speed reaches the full 100mbps. 3 transfers: Three sshd processes run at around ~45% CPU usage, and the transfer speeds seem to jitter whenever other processes need CPU time (I actual (Hardware)