Why does download speed slow (way down) when not viewing the Bandwidth tab? And speeds back up when you click back on Bandwidth tab. Certain other tabs also allow it to speed up. But most do not.
Its as if the program CPU use? Or Networking context switches and no longer concentrates on the Download/Receive task(s).

What kind of system are you using? Is some kind of brutal energy-saving profile enabled?

Long thread: https://forum.tixati.com/support/5814
My short explanation: https://forum.tixati.com/support/6640
Very short: The bandwidth tab takes the least CPU time to render. Other tabs that contain text suddenly became slow after a Windows 10 update, it slowed down all text rendering. This eats CPU time that should have been used for down/uploading.

Thanks notaLamer for explanation!