Animating with inverse kinematics, or creating any complex animation, can result in many keys, which can make editing the animation difficult. In the case of applied inverse kinematics, 3ds Max generates a key on nearly every frame. Often, the same animation can be produced with fewer keys. Having fewer keys in a track makes it easier to change your animation.
Simplify Curve analyzes the pattern of keys in a block of time and creates a new pattern of fewer keys that produces nearly the same animation. You can specify how closely the new animation matches the original.
To reduce keys:
Hierarchy list, highlight the tracks whose keys you want to reduce. Simplify Curve works only on highlighted tracks. You can use any of the above methods to specify different ranges for different highlighted tracks.
3ds Max opens the Simplify Curve dialog. This dialog has a single Threshold parameter.
Raising the Threshold setting results in fewer keys after simplification. The higher its value, the greater the reduction.
Observe the results. If you are left with too few keys, press Ctrl+Z to undo, then lower the threshold and reduce the keys again. If too many keys remain, increase the threshold and reduce keys again.

Opens the Simplify Curve dialog.
Sets a threshold value. Higher values result in fewer keys.
Accepts the Threshold setting and reduces keys as follows: