Granted, I'm on a not-so-new CPU, an Athlon 64 3500+ (no dual core lol) 2.2ghz but when I first installed Tixati and added the first torrent for testing, it went smoothly, no hick ups, just perfection.
Then started adding my seeding queue and it still ran normally.
Three days later, now with twenty six torrents seeding, I tried to add somethings to download, eight single file torrents, to be exact, from 1gb to 2.4gb, to download to a folder then move on complete to another.
The allocate process slowed things down, as expected on such an old PC but even after it was over, the download process would reach 60-90% CPU usage only down going after stopping every single downloading torrent. During the high usage, the Tixati GUI was horribly unresponsive, taking about five to ten seconds to display a torrent's right click menu and weirdly not slowing down the rest of the OS, with Full HD video playback still working normally.

I'm on Windows 8.1 64, Athlon 64 3500+ 2.2ghz, 3,5gb DDR2 RAM, GeForce 210 1gb, 1tb WD SATA HDD, 500gb Samsung SATA HDD, 120gb Seagate Barracuda SATA HDD

I should've said that the high CPU usage doesn't stop as long as there is a single download going on, making the UI unresponsive turning every single action, from maximizing/minimizing from/to tray to stopping a torrent, a slow one, since everything takes five to ten seconds to be executed.

I think you shouldn't move on complete to another folder. If you want to store your completion torrent to any drive (physical/logical), just point the download to that drive. The reading and writing to another drive  can extremely slow down your computer. Hope this help.

I have a Core 2 Duo laptop running at 3.45GHZ, so it's decently speedy. I just installed Tixati 1.99 today and integrated all of my torrents into it so it has been checking all the torrent data for corruption. It was using about 80% of a core for a while but not it's down to about 60%, but, the hard drive is not as active as before so I don't know what the bottleneck is with checking the integrity of my torrents. I hope CPU usage goes down when it's done checking all the torrents, I have about 5 that are downloading and about 15 seeding.

So after it was done checking the integrity of all torrents, CPU usage went down to about 10% of a core and about 80MB of RAM usage. Fairly good. I'll may use this as my primary bittorrent client.
Tribler when trying to download 1 torrent in highly anonymous mode often pegs 1 core and uses a bit over 200MB of RAM, so, Tixati is looking good