use camera path farme range

[math maxer]

in my moving animation
when i use "use camera path" in my 750 frame animation the "GI Rays" scattered along the path of my animation and that required High number " GI Rays" to give acceptable GI result, and increase total rendering time
I am confident that the "GI Rays" i calculated in frame 0 will not used in frames 500-750 [in my animation at least] so is there anyway to limit the camera path calculation a frame range ????

i tried manually change animation time range but i Confused with overlapping frame

[math maxer]

in my moving objects animation
when i use "use camera path" in my 750 frame animation the "GI Rays" scattered along the path of my animation and that required High number " GI Rays" to give acceptable GI result, and increase the total rendering time
I am confident that the "GI Rays" i calculated in frame 0 will not used in frames 500-750 [in my animation at least] so is there anyway to limit the camera path calculation to a frame range before and after my current rendering frame????

i tried manually change animation time range but i Confused with overlapping frames

and sorry for my bad english