I know this has not been updated to v4.x yet, but I would buy it for you when it is!!!!!
https://community.invisionpower.com/files/file/5166-ignore-topics/
I would LOVE to be able to ignore threads that I have no interest in, like the pokemon and yu-gi-oh ones. No offense, just my taste and I am sure others would like the same opportunities.
I can never figure out why the ones I have to scroll thru each day and have the most posts are the ones I want to ignore the most.......