Of course the problem is worse the faster you go from the extra air flow. That extra air flow is not the problem, though. It's just pointing it out. You have got too much slop in your linkages. Sit and idle and put your wipers on high. The extra force of the higher speed may show the problem too. Your linkage is allowing that wiper to move too far, it doesn't make any difference how strong that spring is, the wiper should not be moving off the glass in the first place.
