BF3 was the same, I laid off for 12 months (due to not being able to play it) - after that, it was a PAIN in the ass as a level 1 fighting against level 100's with all perks and weapon unlocks. But, running around as a medic dropping med packs got my levels.
Also, EA released an update for the servers for the "crashing" as well as server queing (Server queing could be a delay for all servers to update). This came out today on the BF4 Forums.