Remove sections of content from Quora.com
Interesting question,


I would place the bulk of your comments on top, they stop the flow of the reading
I would experiment with $.remove() instead of $.hide();, otherwise you might actually run into memory and performance problems. I am thinking that with $.remove() you might not even need the timeouts any more.
Manifest looks fine
Your indenting is off, use something like jsbeautifier
This is shorter and more readable 

$("span:contains('Top content on Quora')").closest('.pagedlist_item').hide();


than

var $topContent = jQuery("span:contains('Top content on Quora')").closest('.pagedlist_item');
$topContent.hide();