I read that we're recommended not to use the junk filter, however I receive so much junk that I decided to give it a go. I've never had problems with PTB freezing or crashing, but some other strange things have happened.
First, it's not catching 50% or so of the junk messages that go through for some reason. It's also marking messages as 'junk' that have never been marked before, and are on a whitelist.
Second, the message filters act weird, too. They filter messages that don't even remotely match the rules to that filter. For example, one message this morning was placed in a folder that only receives messages moved because they contain exactly "ing@." Upon looking at the folder, the mail was marked junk and moved to the junk folder. I have also had issues where after a message is moved by a filter, upon clicking on the folder it marks it as junk and moves it, even though it is clearly not junk.