Ideal braking?

Hello!

After around 100 laps on the Mugello F40 Rivals, I managed to get a 1.00.22 laptime. I can run 1.00.7 for days, but even getting below that is a real struggle.
My problem is that I dont really know what I’m doing wrong. I’ve watched replays to find out where to brake, which line etc, yet, my speed is pretty terrible compared to the top guys. Something I do have noticed tho, is that sometimes when I release the brake quickly, instead of smoothly, its like I get a boost?
Is there something do it?