The large steps at the beginning have to do with your torso angle and foot position relative to your knee. Because of the rather acute body lean from a proper 40 start, your foot placement will always be behind your knee which drives you forward. By maximizing your stride length in the first ten and maximizing your lower body starting strength (heavy deads and Olys), you will cover more ground in fewer strides. Don’t worry, it just feels slower, but in my experience, other than pure strength issues it is the key to the 40. In looking at your first post, work the hell out of your start and your 10 and your 40 will improve. Don’t forget the 2 foot start! Practice, practice, practice.
you say your start is costing you. In a show i saw sprinters just running 5 metres from when there coach clapped there hands,they did it 20 times
why ,improving there reaction time to the stimulus
maybe that could help getting off the blocks sharper.