I think the speed is fine, it's more the precision.
Something I use to encounter in old gun-con games on PSX (when you didn't have the Gun-con), or arcade shooters ported to PC, was an additional button to control the speed, kind of like a run button. Some games let the reticle move faster when you pressed it, and others would let you slow down and be more precise when you needed it. I don't know the specifics of your game, but one of those could be a better-balancing alternative.
Hope that's helpful in some way!