>>/18993/
Refreshing the whole thread with F5 takes a long time, I imagine most people use the ajax refresh, pressing the button or waiting for the automatic timer event. But it only adds new post, it doesn't remove those that were deleted. Not really relevant for most boards, but you know what it's like in /polru/.
 >>/18988/
Dollchan extension tools has this functionality. It displays a "deleted" span against each deleted post. You can inspect that element, and write a regex spell that would filter all posts that contain the html code for that element. This way all deleted posts will be automatically hidden by dollchan.