So, when I'm on a certain horribly inappropriate disturbing terrible NSFW imageboard (not 4chan), sometimes the scrolling stops working, and then I have to reload the tab for it to work again. It MIGHT have happened on other sites, but I'm not sure...
This normally wouldn't be so bad but on this particular website, when you reload the page it takes you off of the thread you are currently in and back to the main page, so you have to find the thread all over again which can be really annoying unless it's on the first or second page. Also, you have to scroll back down to find where you are, and some threads are really, really, really long.
Also, I hate that checkerboard thing that shows up when you scroll down. Especially on Tumblr. Just saying.
You might try turning off javascript in the Browser Options. In the Browser, swipe down, on the left pick Content and try disabling java and/or Flash. Then again, it could be the site.
