The "processing speed" issue is one I have as well - a combination of processing difficulties and tinnitus can make it very hard for me to understand what someone is saying, but often I'll figure it out right after I say "what?" People I hang out with often know that "what?" means "working on it" as often as not and don't mind when I interrupt.
The problem I run into outside of Known People is that people will interpret "what?" as not understanding instead of not parsing what was said, and they'll launch into an unnecessarily explanation which (a) makes it harder for my brain to catch up to what they said before because now it's trying to parse New Info and (b) results in them thinking I'm rude when I cut them off with an answer. Have you had any luck dealing with it in those kinds of situations, or does it not usually interact that way for you?
no subject
The problem I run into outside of Known People is that people will interpret "what?" as not understanding instead of not parsing what was said, and they'll launch into an unnecessarily explanation which (a) makes it harder for my brain to catch up to what they said before because now it's trying to parse New Info and (b) results in them thinking I'm rude when I cut them off with an answer. Have you had any luck dealing with it in those kinds of situations, or does it not usually interact that way for you?