Hello there,
When I download the same torrent file in Windows Vista through BitTorrent,it is fast e.g., 100 Kb/s. But same torrent file runs too small in Fedora through qBitTorrent v0.9.3 e.g., only 25 Kb/s. are there any changes in need to make in preferences or Is there any other software for torrent downloads with improved performance?
Best Regards

There could be many reasons for this. qBitTorrent might not have the features enabled like Peer Exchange or DHT. Otherwise they could have been completely left out of qBitTorrent and in BitTorrent (which I know those are).

You're best to use a better torrent client for Fedora. rTorrent is the good. Others like KTorrent or Transmission I have not tested really but people use them.
Otherwise uTorrent with Wine works good and is fully supported.

Other than that *nix should be superior for handling mass connections required by torrent clients over Windows.

Thanks FireRaven