Realms of the Mad God uses Anti-Cheat Toolkit (ACTk) for their client-sided speedhack detection. Since there seems to be no anti-measures implemented against simply unloading the ACTk. We might as well just do that.
This MelonLoader mod allows you to speedhack in the game. It isn't much, but you can make the game run around 1.15 times (15%) faster using something like Cheat Engine, which is a nice DEX/SPD boost. Going higher is possible when your ping is high, but can and will result in a game kick (this game doesn't seem to like banning cheaters, instead, they only react if there is a support case, like claiming the gold from an in-game item or recovering an account).
Credits: @mimination