There is not, and most likely never will be. Paizo had the opportunity to fix this mistake when they first released Pathfinder, but they did not do so which means they must be under the impression that this lag is appropriate. Unfortunately, they’re wrong, about that and many other things (they really don’t understand their own game all that well, nor do they seem to very much care). Eliminating that delay is step one for redressing imbalances between prepared and spontaneous spellcasters. But they have a general policy of blindly insisting that core is balanced and refusing to admit any flaw therein, so anything at this point that fixes the situation would be against that policy.
That said, it is entirely possible to go too far. Races of the Dragon had the draconic rite of passage, which was fine, but it also had the eminently-abusable Dragonwrought feat, which... should probably be avoided, or at least used minimally. For example, using Dragonwrought to take loredrake, and advance several levels past the wizard in spellcasting. The web enhancement is better; the greater draconic rite of passage was an obnoxious feat tax, but at least it existed (and wasn’t the absurdity of loredrake), and the web enhancement also had the rewrite of the kobold race that was quite good. So simply importing 3.5 material on this subject is not necessarily a great choice either. Some of it is good, and some of it is bad.
My recommendation is that sorcerer (and similar) spellcasting change like so: at all levels but 1st, 2nd, 3rd, 19th, and 20th, their spellcasting is what they used to get one level later (so 4th works like 5th used to, and so on). At those levels, see this table:
| Level |
1st |
2nd |
3rd |
4th |
5th |
6th |
7th |
8th |
9th |
| 1st |
3 |
— |
— |
— |
— |
— |
— |
— |
— |
| 2nd |
4 |
— |
— |
— |
— |
— |
— |
— |
— |
| 3rd |
5 |
3 |
— |
— |
— |
— |
— |
— |
— |
| 19th |
6 |
6 |
6 |
6 |
6 |
6 |
6 |
6 |
5 |
| 20th |
6 |
6 |
6 |
6 |
6 |
6 |
6 |
6 |
6 |
This results in a smoother progression, and greater balance between spontaneous and prepared casters. It does not wholly close the gap between the two, but it helps considerably. If you are looking for more improvements, see the discussion I linked above.
If you do this, you’re better off than 3.5 or Pathfinder. The greater draconic rite of passage worked, but it was obscure and kobold-only; there’s no reason for that. It also became a mandatory feat tax to play the sorcerer class well, which again, there’s no reason for that.
Finally, one last note on balance: this change improves balance between sorcerer and wizard, and similar spontaneous/prepared pairs. But 9th-level spontaneous spellcasting classes are some of the most powerful in the game—really only beaten by the 9th-level prepared spellcasting classes. In reality, both of these should probably be nerfed. This answer doesn’t address that, though, because doing so is quite difficult.