not exactly an "accent" on the first not, but a short impulse necesarily followed by relaxing all hand. also, what helps me on "speed" is a very small and constant move on the hand - the verso of the palm (i don't know what it's called) left-right, just to add the fingers. also, remember, if you have to play on a piano with a harder mechanism, you need to move you fingers more.
as an exercise, i would suggest beginning at a very slow tempo, (say quavers at about 120), and slowly increase the speed. also, try this exercise on all combination of fingers (1-2, 1-3, 1-4, 1-5, 2-3 and so on). helps if you work with both hands with exactly same fingers.