Without seeing your footage nobody can advise.
What you are doing is called Rotoscope. It seldom requires you to adjust keyframes for every frame. The trick is to use as few as you can. If I were trying to roto someone's eyes I would use AE's built in tracker to stabilize the footage using the corner of one of the eyes because that would probably stay the same throughout the shot. I would then add a colored solid (blue or red would work) and set the blend mode to screen so I can se through the solid. I would then start at the first frame and use the pen tool to create a mask that covered the eye. I would then move down the timeline until the mask needed to be adjusted and make adjustments. When the mask was exactly as I like it I would add a null to the composition, then add an expression to the null that tied the null's position to the stabilized movie's anchor point. Returning the CTI to the first frame and then parenting both the roto layer and the stabilized movie to the null will remove the stabilization from the move and add the movement to the roto layer. In this example I needed to adjust the exposure on the right eye so the roto layer was used as a track matte for an adjustment layer. Even though there was a bunch of movement of the actors head only a few keyframes were required for the roto. The first screenshot shows the blue solid visible so you can see the mask, the second shows the final result. The whole process took about 6 minutes.
As Mylenium said, if we saw your shot we would have a much better chance of suggesting an efficient technique.