Try this:
1-Set outgoing speed limit to 70% of the max upload speed offered by your internet service provider. More details here:
2-Reduce these numbers:
- Connected peers per download/upload
- Maximum concurrent outgoing UDP/TCP connection attempts.
- Download/Upload slots.
3- If Tixati port is open, and you get a high number of incoming connections, try closing the port temporarily for troubleshooting.
By the way, when Tixati becomes slow, do you notice any problems browsing the internet?