I can at most get about 240 mbit/s (30 MB/s) when using tixati, while using the "Bittorrent" client, i can get 456 mbit/s (57 MB/s) on the same torrent.

* Port is forwarded and working
* DHT is on and working
* Bandwidth limiters are OFF (and no i do not want to enable them!)
* CPU Usage is basically 0 before, while and after the tests
* OS is Windows 10 64 bit
* I have 24 GB of RAM, more than half is empty

So... can Tixati not handle these speeds?

p.s. the allocating files thing in tixati always takes much longer than other programs, very annoying...

There is no reason that Tixati shouldn't be able to use your whole connection, so something else has to be interfering.

Any antivirus running?

Yes and if antivirus is the problem then i don't want to use that torrent program.

Bittorrent is working pretty nicely, but if you have any sensical tests let me know.

Try 2.18, it "feels" like it's able to handle my 100+mbps connection a little better.

try 2.19 is out now, good luck

There's no reason why ANY torrent client shouldn't be able to use up your full connection speed, whatever it is (even a relatively slow one, such as yours). Torrent clients do not limit connection speeds, unless you configure them to. Settings such as the maximum number of connections and peers per torrent, or the port(s) you're using are some of the things which CAN affect it.

I would try Tixati's optimization guide, if you haven't yet:
http://support.tixati.com/optimizing%20tixati

It's easy to test whether your security software is the cause by simply temporarily disabling it to see if it changes anything (but I don't see why it would be, since you already said your ports are forwarded, and that would be the one factor which would cause a problem with speeds).

Please do note that testing torrent client speeds is always relative, since you can't necessarily expect the same exact performance out of two consecutive tests, even if everything else in the test is the same. Torrent speeds are variable and erratic by definition, depending on a multitude of factors (number and speed of seeds, number and speed of downloaders, relative location of seeds and downloaders, network congestion, time of the day and time zones, local software issues, and many others).

Hope this helps, good luck.

Speed tests over loopback/ Windows
===================================
Test conditions:
-Using multiple BitTorrent clients on the same computer over 127.0.0.1 loopback.
-The files being transferred are all on a ramdrive (almost 5 GB DDR3), so effectively ruling out slow drives as well.
-CPU is Intel i5 650 3.2 GHz -- dual core with hyperthreading.
-Unless stated otherwise, these speeds are all UPLOAD speeds to uTorrent v2.2.1.
-The test is a single TCP connection at a time -- 1 seed to 1 peer, which may show severe pipelining issues. Multiple seeds to multiple peers could be faster depending on program designs, but would certainly cause a much larger CPU load.
-As many settings as possible were disabled in the various BT clients -- no DHT, LPD, trackers, uTP, and even half open connections were set as low as possible since only 1 connection had to be made. Were more settings enabled, CPU loads should be higher. Peers were manually added to the torrent so even a local tracker was unnecessary.

*Tixati v2.2.5 -- 55 MB/sec peak and sustained 30 MB/sec. ( maxes out a CPU core -- 25% of CPU's max as it has 4 virtual cores)

Notes:
Seems Tixati acts single-threaded and is unable to spread its CPU load between multiple cores.
When I set other very high CPU-using apps to highest priority and Tixati to lower priority, its speeds plummeted -- it even stalled out and crashed once.

*Transmission v2.84 for Windows -- 37 MB/sec often being unable to sustain an upload speed over 20 MB/sec (CPU usage: at 2-5%...)
Tixati to Transmission is a "blazing fast" 8 MB/sec.
Transmission to Tixati runs at 12.5 MB/sec.

*Deluge v1.3.12 -- 101 MB/sec. (CPU ~36% , ~40% in non classic/BG mode)

*uTorrent v2.2.1 -- 130 MB/sec, 100 MB/sec sustained   (CPU: 25%) -- this was uploading to qBitTorrent.

*qBitTorrent v3.3.0beta --  130 MB/sec, 120 MB/sec sustained (CPU: 33-36%)
qBitTorrent to Transmission strangely also runs at 8 MB/sec. Transmission is at 2% CPU...qBT while uploading to Transmission is bouncing between 0-2% CPU.
Transmission to qBitTorrent runs at 111 MB/sec.

Notes:
-Both Deluge and qBitTorrent use libtorrent, so results are similar.
-uTorrent writes whole pieces in 1 go,  qBT and Deluge do not:http://forum.deluge-torrent.org/viewtopic.php?f=12&t=36959
-Deluge 10 Gbit/sec seedbox results:http://forum.deluge-torrent.org/viewtopic.php?f=7&t=53423&sid=2ade6937d0d00f986802f924f10910b2
-multi-file torrents are slower than single file torrents of the same size:https://qbforums.shiki.hu/index.php/topic,2627.msg12725.html#msg12725

Conclusion:
Even with the fastest possible connection and storage devices, common BitTorrent clients are likely incapable of significantly exceeding 1 gigabit/sec (~120 MB/sec) transfer speeds due to their complexity and/or lack of parallel processes. The tests were typically bottlenecked by my "slow" CPU. If I disabled hyperthreading, a BT client could use half my CPU and possibly be faster.

Just have to say, I have tested huge amount of different torrent clients, and Tixati was the fastest.

Tixati Settings -> Connections, try the following,

Maximum peer connections per transfer --> 200
Maximum concurrent TCP outgoing connection attempts --> 150
Maximum concurrent UDP outgoing connection attempts --> 500

and in Advanced Socket Options click Edit, click presets and select compatible. After that edit the following lines and leave the rest as it is.

udp_rcvbuf_def = 1048576 // def=65536 min=4096 max=1048576
udp_sndbuf_def = 1048576 // def=16384 min=4096 max=1048576

upc_sndwnd_maxpkts = 16384 // def=510 min=10 max=16384
upc_sndwnd_maxpkts_mtu_percent = 500  // def=50 min=5 max=500
upc_rcvwnd_maxpkts = 16384 // def=510 min=10 max=16384
upc_rcvwnd_maxpkts_mtu_percent = 500  // def=50 min=5 max=500


And remember to share and upload =)

And always test the new Tixati version for improved speed.