I've checked on Enomther's build I'm running, which is also AOSP ROM. The most significant correlation of GPS lock time I've noticed was only with data connectivity rates. I've used GPS Status, and it took ~5-10 seconds to lock both in the open near my house and on the moving train at 150km/h in a significantly changed location, with the only thing being common - there was good 3G reception in both areas. Both times it locked in 2 "batches", 3 satellites being locked in the 1st one, and another 5-6 in the 2nd one. The first "batch" is probably strong satellite signals that were locked after Almanach download almost immediately, and the other "batch" might have been post- Ephemeris download. Either that or it has gpsonextra functional - but in any case, the lock is super-fast when the data rates are good.
On the other hand, the data registered on Traffic Info is only 40k download and 20k upload - even on GPRS it won't take long. But the base station needs to support aGPS - that's also something to consider.