You must not do spawns or PVP on Great Lakes! There are players here who wait until the spawn your doing "pops" then they raid you and grab all the stuff killing those who worked there buts off to bring it to a close. With their 3rd party cheats the group doing the spawn ends up dead, looted and without reward. The Devs have done little to nothing on Great Lakes to make cheaters "vanish" on this shard, they are alive and well.
Sorry to bite on this but.. uhm ever hear of a stealther? If this is such an issue then I suggest you make a tracker/detect hidden toon so you can find the stealther. If not then always assume the worst and prepare on 4th? In terms of cheaters, aside from there will always be cheaters, it's pretty damn easy to spot them. Drop a poison field and watch the guy chug cure potions back to back to back with no effect for no reason. The speed issue is so varied, 2d vs EC, the computer they are running, the internet connection the person has as well as where the server is located, all effect speed. I know a lot of people who are extremely fast, yet they post screenshots with full taskbars. My point is just because someone is fast or shows up to raid your spawn when you pop the champion, doesn't mean they are cheating. Another take on these "cheaters" could be to outsmart them. Get raided, die and then bring your thief in to steal the good scrolls after they kill the boss. A lot of uo is outsmarting your opponent, not branding people a cheater because they have bested you.
Now if they are running threw weird objects, casting and running or some such thing, then yah they probably are cheating, and so use your brain to outsmart them, as most of these people are cocky knowing they have an advantage already, and are easily lured into traps and the like.
If you still can't win, then make a sampire, farm up something people want and get your powerscrolls with gold. A lot of pvpers spend an awful lot of time on their characters, learning and improving, so don't hate on them for being good at what they do.