Have you tried talking it through out loud? It sounds odd, but it helped me! I went through a phase where it took me hours to leave the house because I was paranoid about switching everything off in case there was a fire...and then I'd get to the front door and panic I'd forgotten something and have to go through the whole house again. Then I tried this - I would stand in the middle of the room, pointing at all the things I was worried about in turn (light switches, sockets etc) and saying 'that is switched off, it is safe now'. When I finished, I'd go out of the room, shut the door and say 'that room is now safe'. Ok, so it took me a while to get out of the house, but not nearly as long as checking all the switches 25 times each!!! I also found that when I did this, I was less likely to panic away from home and if I did, I could stop myself by reminding myself that I had checked everything.
So maybe in your case, stopping to watch the washing machine for a moment and saying 'the washing machine is cleaning thoroughly - I don't have to worry about what is on the material any more' or emptying the vacuum cleaner into the bin 'I am getting rid of this, I don't have to worry about it any more'. Might be worth a try (only make sure no neighbours are listening in or they'll think you are potty - someone once saw the tail end of my house-leaving routine as I walked out the front door and I'll never forget the look of horror on their face
)