Animation full - light cache - use camera path

Nope, with options "use cam path", the LC computes for all the path of camera, but for each frame. That's to try to put samples at same place, at least for static objects...

If Gi is not much affected AND if the door don't take too much size in final image, i suggest an efficient and fast method :

- hide all moving objects.
Render the anim for the static geometry using the flythrough method.
- unhide the sliding door
- then, place a surrounding sphere gizmo on your sliding door (give some good margin)
- activate a VrayshpereApparatus in environment effects
- render using the full anim wizard
- composite the results ! if you've problems with premult, tweak the color of the VraysphereApparatus, or put your prerendered flythrough frames in background when rendering the animated part.
The sphere helps to not render all the scene, but only the area where the slinding door is. This can help you to gain render time