Having some issues Editing Sprite GIF animations, not cause i cant do it but cause GIMP is way to slow to Do so.

so anyone know where to find a quick and easy "copy, past in" like GIF editor.
but MOST important thing, it cannot change the colors, i had another witch was easier but when ever i saved it made the colors slight lighter, witch causes... lets just say "issues".
(Also it needs to be able to add new colors not already in the picture.)


Help anyone? its for a project, and its reeealy slowing me down at this state.