if I turn on ipv6 while running dht in tixati my router fritzbox 7490 goes to 100% cpu usage and makes internet unusable for everyone else.
since i can't find anyone else having this problem I'm guessing its unique to my settings but I have no clue what the cause could be.
no other program has caused this to happen either.

what OS and version of tixati?
are you sure that your router can handle ipv6?
if you turn off DHT or close tixati, are things normal?
in settings-network-connections what is the network mode set to?
any changes to the default settings?

win 10
tixati 3.31 (has been an issue for several versions)
yes other then with tixati ipv6 has been working fine
yes turning off dht closing tixati or setting network mode to ipv4 fixes it immediately
yes I have changed several other things incoming port for example witch I made sure is set correctly in the router to allow all traffic UDP/TCP ipv4/6
I have also done packet capture both from the router side and on my pc and the ipv6 traffic looks normal as far as I can tell

I think it's going to be a router issue. It may handle IPv6 on the CPU instead of a dedicated network chip (keyword is "hardware offloading"), and that could result in high load when handling too many IPv6 connections at once. Ask the manufacturer about it.

Instead of turning off IPv6 entirely, set the Network mode to "IPv4 Preferred" and see if it has an sensible effect.
Also test Tixati's portable version with DHT, but no active torrents and see if it has an sensible effect.

OP, this is definitely a problem with your router and it's handling of IPv6.

It isn't a problem with other programs because they only connect to a few hosts at the same time (eg. web-browser).  The DHT has to send and receive datagrams from dozens of different remote hosts at the same time, so if your router has weak IPv6 performance, it will become a logjam when pushing DHT traffic through it.

I managed to fix it!
I switched the router from native ipv4 to native ipv6 mode which in theory shouldn't do anything since both connections shouldn't use any translation but I guess it was using some cpu intensive translation mechanism for ipv6 anyway