For an increase in swimming speed of 10%, decrease your drag by 3% or increase your power by 30%.
Read that again.
Now, it seems like it's easier to drop 3% drag than gain 30% power. You're mostly right. IF.....IF the drag is related to swimming technique - that's a motor control issue. It might be harder to change drag if the technique relates to a mobility issue that prevents being able to get INTO a streamlined position. That takes trained movement assessment to reveal the region of concern, then trained local biomechanical testing to find the reason for the regional mobility dysfunction, then trained reset techniques to bring the local biomechanical dysfunction up to minimum competency.
Here's a video of a Chinese swimmer doing a Y-hold with flutter kick. What can you see that might limit speed according to the above equation?