Well. You guys are complaining about the speed potions... It costs 20 for 90 seconds of speed. You can afford it yourself just by opening 2 chests and then the "diamond" won't catch up with you that easily. I don't understand why you guys think that the speed potions are such a big deal.
Maybe take a look at the poison. You can farm a lot of loot and 1 gap costs 125. A poison cost 150. If you hit a poison perfectly on the enemy, then you'll be able to make him waste 3-7 gaps. That's like 400 - 1000 coins, that you waste in just a few seconds. I think that is a real problem.
Maybe we should talk about the invisibility potion too. I won't sound selfish but I'm one of those guys who have played Assassinations quite a lot so I'm pretty good at it, and for me, it's not a big deal to get diamond. But every time I got diamond and I have a diamond fight with another guy. When one of us dies the other guy doesn't get the chance to pick the loot up before an invisible guy comes and steals it all. I think it's a nasty way to get your stuff. Really undeserved and sad for the guy who actually did something and killed the other one.
Well, I just want to say that the speed potions has nothing to do with Assassinations. They're one of the smallest problems at the moment. Hackers have always been a problem in Assassinations but all the player kinda got used to that :)