theres a couple of different lines through 1+2 depending on your skill level, if you carry too much speed through turn 1 theres no way to correct it before going off track before turn 2. one of the fastest ways for me was to brake just before turning into turn 1 and using the weight transfer and slight drift to be setup early for turn 2. your tires regain traction right as you need to get back on the throttle and (depending on your gears) you never need to leave 4th. just don't forget you diaper though lol.
same for turn 4, i don't brake. I lift just as i hit the right side curb and start to turn left. I immediately get back on the throttle after about 15 ft. the lift starts your rotation and when you go over the left side curb it kind of keeps you pulled in and you can stay on the throttle for the whole turn.
after the hairpin coming out of the tunnel it is better to go a bit slower through the hair pin so you don't need to lift on the left hander going uphill. that small lift turns into a full car length by the time you get to the last big turn.
running this track reminds me of a documentary i watched about jackie stewart. it might still be on netflix. he was at monaco and explaining how typically you brake, turn in, and then use throttle at the apex on exit. then he explained how all of his turning would be done before the apex and he was back on the throttle well before he reached it. Now it might just be my car (cause i do like'em a little loose) but I was able use those techniques on the majority of this track. during testing I ran a hotlap of 1:09.8xx and could have done a hair better on the last turn. hopefully the testers can do the same