It's easier said then done, in my opinion, I'll try to explain it as clear as I can, if that doesn't help, go to YouTube and search a time attack on-board cam or best motoring
My take on Tsubuka is, you'll have to use every inch of the road for your out-in-out line, now, the first hairpin, after passing the apex getting out from the corner, there is a extended area looked like grass but its actually concrete, using that area will make you pick up more speed when exiting,
before entering the second hairpin, there is a same kind of area on the right side of the driving line, you'll have to ride allover it, and if you look closely, the apex of this hairpin actually has the same thing, literally It's just like Mario kart, you kind have to see that as a shortcut, so does the rightside after you pass the apex.
The next corner is the one before the Dunlop arch, same thing, apply out-in-out, pass the dunlop arch, there is a gray grass/concrete area left of the driving line, the next corner is a left so You will see a somewhat chicane on the right of you driving line.
Now, the very last hairpin, passing the apex you'll see the extension on the left of the driving line, you have to use that area so that you can pickup your speed before entering the long straight.
And the very last corner, the most important one, on the left of the driving line before the finish line, there is a huge, huge concrete surface, you have to make sure you pick up your speed in the very last corner, people often times go way slower due to not seeing the apex when entering,
What you want to do now is speed up so that the car can use that extension as a part of straight before going in to the first hairpin for your next lap. if you didn't pickup enough speed on the very last corner, you won't hit top speed before you start breaking for the first hairpin(which is around 110-113mph, give or take). Which ruins your next lap
A general idea is that using the chicane mentioned above, you will be able to get full throttle earlier than normal way of driving, however with a 10 lap race, consistency will play a crucial part as well, I'd sqy if you can do 5 laps under a minute, you should be able to take the win
Just my 2 cents after spending this whole afternoon try tuning it tho, might not work for everyone
I typed this on my cell phone so if there's any spelling mistake, let me know LOL