Wayne gives some pretty complete responses to this here:
https://blog.cgcookie.com/forums/topic/tip-cpu-only-gpu-only-or-both/
https://cgcookie.com/questions/12812-i-can-t-get-rid-of-this-knee-pop#answer-44082
https://blog.cgcookie.com/forums/topic/is-spacing-dependent-on-timing/
It’s tough because there are so many things that can cause this.
Some typical culprits:
Hips aren’t rotating/translating correctly
Foot IK is stretching too far the frame before
Foot leaves/contacts the floor too early
Toe isn’t rolling off the ground completely
It takes a lot of practice and developing your eye studying reference to identify what specifically needs to be done. Could you post a video of your cycle from the front and side? Getting another set of eyes on it could help identify what’s going on faster.
