I recently found this video which put an issue I have in better words than I could have ever put them in myself. I shared it with someone to explain how I experience certain things and they proceeded to make this funny adaptation of the ADHD version posted recently. Hope this gives the context/explanation you needed.
Definitely varies from case to cae because I usually don't have over processing problems when I'm in a group of people, but when I'm in my head and not focusing on anything, I'll go on and on processing a lot and constantly swap what's going on in my head at what can feel like a topic every few seconds (even if it means swapping to a past topic from a few seconds ago).