A 4e PC is roughly equivalent to an Elite monster of his level - ie 2 standard monsters. A Solo of PC level is a moderate challenge for a 5 PC group, roughly equals 2.5 PCs.
A 3e PC is not really equivalent to a monster of CR equal his level, for the monster to provide a 'moderate challenge' for a 4 PC group it has to roughly equal 2 PCs.
So a CR 3 3e monster equates to a level 3 Solo 4e monster. IME the result is that 3e/PF PCs do advance faster than 4e PCs, but not nearly as much faster as the OP indicates.
Edit: Even running published modules, giving XP for treasure, & bonus XP, 1e or Classic is not as fast as
3e/PF IME. I recently ran Pathfinder AP on Medium Track and in the single digit levels the PCs were levelling up every 2 sessions, whereas in 1e or Classic it's closer to 5 sessions. 5e is the fastest at one level 1>2
and one or two 2>3, then slows down to a more normal pace of 2-4 sessions/level up to 10. It seems to speed up again after 10.
Time to Level:
1e: Gygax suggested a year of weekly play 1-9, then a couple levels/year thereafter.
Classic Rules Cyclopedia: Suggests 5 sessions/level, so 1-10 in a year of weekly play, 1-36
about 3.5 years. In practice IME there is a slow spot around 6-8 and I expect levels 26-36 go
fairly fast.
3e: Stated aim 1-20 in a year of weekly play. Seems possibly right if no death penalties, otherwise 1-10 is about half a year but 11-20 seems to take longer.
4e: Stated 1-30 will take 1.5 years weekly play at max rate, but most groups will be slower.
IME is much slower, 4 sessions/level and would be closer to 2.5 years.
5e: Seems to be designed for 1-20 in a year, but with irregular advancement - very fast 1-3 and
11-13, slower 8-10. Suggests 2-3 sessions/level, so 20 levels would cover 50 sessions.