Thanks MxxCon for giving us the heads up on this update. The official BitTorrent 3.4.1 has been released and all users that uses the official client are encouraged to upgrade. The new release features the fixed tracker problem found in 3.4, thus, utilize the bandwidth more efficiently. Here's the changelog:
Client no longer complains of connection to tracker problems when transfers are still working
Lots and lots of bandwidth savings (the 'compact' tracker parameter)
Better support for peers with dynamic IPs (the 'key' tracker parameter)