Marked as Won't Fix because Matinee is being depricated
Frame rate issues using Fixed Frame Rate and Matinee. This could be similar to some issues involving "Force Fixed Frame Rate".
1. Launch a Third Person Template project with -usefixedframerate -fps=60
2. Move around the map, take note of the spinning tutorial icon and the clouds in the sky
3. Cinematics>Add Matinee
4. Repeat Step 2
Result: Camera navigation is very sensitive now, sky material is panning much faster, and the tutorial icon is spinning at light speed
Expected: Performs the same as when the scene was first opened
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-34524 in the post.