If you went from 13 to 22 based off the great scientists I have to think you never went caste system in this game and are on only your 3rd or 4th great person. Go caste plus pacifism earlier, pop a golden age, pop 6-7 gp in a few turns, then by the time you research sci method you'll hardly notice. You'll go from like 50 turns to 55.
I was using caste system and on my way to my 8th GP. I had just finished a golden age in which I popped 2 GPs. I have never managed to pop 6 (let alone 7) GPs in a GA.