Not sure if this is already done in IL runs, but if you have boost available before the end of a lap, don't switch to white. Instead, boost alongside the pad, carrying the speed past the jumppads and onto the track. Can save between half a second and a second (on average, white boostpad to finish line was 4.75s, but boosting when black was 4.00s). If you do it on lap 1 or 2, there's then a black boostpad at the start of the next lap, but you'll want to switch soon after.