I recently changed over from Qbittorrent to Tixati and before that had Deluge and uTorrent.

I am on a 100mbit line and haven't had this issue before. When Tixati is open I cannot browse the internet. Using Google Chrome as my browser pages fail to load and Tixati is only downloading at 300kb/s. But I've downloaded files via Tixati with more seeders and have downloaded files at 4MB/s but regardless of how fast the downloads are webpages don't want to load with Tixati open.

With Qbittorrent, deluge and utorrent I didn't have this issue even when downloading near max speed of my internet connection.

I've left incoming ports as default 18347 and the connections page is default also.

I am running Windows 10 tech preview

Have you gone to the bandwidth page and limited your out going data to 80% of max? Likely the problem. Click the optimize link at the top of this page and follow those steps.