Hit factor is used to score USPSA matches. It is simply points over time. For example:
We have a simple stage with 10 paper targets, 20 shots. 100 points possible for the stage.
You shoot 100 points in 10 seconds, 100\10=10.0 hit factor.
I shoot the same 100 points you do in 15 seconds, 100\15=6.667 hit factor.
Lets say you win the stage for the match, I score 66.67% of what you did to win the stage. If the stage is worth 100 match points you get 100 points for the stage and I get 66.67 points for the stage.
Speed does play a huge factor, but without points speed is useless. The guys that are winning are scoring 90% or more of the available stage points.
Do the math again, you shoot 60 points, all over the paper but without a miss, in 8 seconds. 60\8=7.5 hit factor. I shoot the stage with 95 points but in 12 seconds, 95\12=7.92 hit factor. Even though I was 4 full seconds behind your pace I win the stage this time.
Balance is what you need. To do your best with your current level of ability, no matter what that level is, you need to shoot 90% or more of the points as fast as you can. You shouldn't let the points slip to gain speed, especially early in your shooting. Whatever speed will allow you to score 90% or more of the stage points is YOUR speed, and is as fast as you should go.
At the top level 90% won't get it done, the top shooters are shooting 95% or more of the stage points.