When I realized you only have to push down on the strings hard enough to sound the note. Excessive Pressure just deadens the note, wears out frets, Slows you down, and tires out you hand.
Feel the neck, literally. Just touch it hard enough to feel it. The day I figured that out was the day I got fast and accurate.
Then there was the day all the "Positions" just melted away, leaving one big scale all over the neck. The day I stopped thinking in "positions" and started playing the Whole Neck, I got better.