The 3 block look ahead may be good for 2D contour or pocketing purposes where it have longer moves; but not enough for 3D, where typical moves are way too short. Gtdinc is complaining for slowing down the programmed F10 feed; I used to have several VMC Haas which has 200 blocks of look ahead, and while cutting aluminum blow mold 3D cavities, I ran them at F100 without noticing any slowing down. Set the screen to show the current block, you must see the blocks flying by. Really don’t know where the threshold for 3D is. Let me tell you my story, trying to improve, I replaced a Haas VF3 for a Okuma MC 4020 (great production machine) but on the same mould it took twice as much time as the Haas did; so in less than 6 months I switched again but to a HaasVM3 ( for me, the best moldmaker machine). Hope didn’t bored out you with all the talk.
Kind regards, Mario