Is there any way to disable the balloon particles that appear on damage in Pyrovision? The problem with the balloons is they are opaque and huge and block everything, making it impractical to equip any Pyrovision item and use it seriously. They are also everywhere, since they appear if you hit anything or are hit.
It looks like you cannot disable the balloons and confetti in pyrovision. What you can do is go into HUD options as discussed here http://wiki.teamfortress.com/wiki/Multiplayer_options and limit the border distortion which might help you focus in some small way. There was also a discussion here about how you could disable pyro vision effects, but still wear the item.