The problem is the DICE/EA's minimum spec trickery.
The min specs are for the singleplayer (as it has always been for ages), not for the multiplayer.
Multiplayer with 60hz servers and real players has different specs.
Because of that most people can run the game in Team-Deathmatch or Redsec just fine but when it comes to a lot of players in one place plus destruction there are so many cpu calculations that the system cant handle it.
The beta ran on 30hz and the CPUs had to calc only half the things it needs to do now.
Found this on YT for reference:
https://www.youtube.com/watch?v=bK5daxCedSo
User comment below this video:
"How much RAM do you have, and is it dual-channel? If you have 16GB of RAM without dual-channel, the game really can't reach 60fps, because the lack of dual-channel and ram limits the CPU's performance in that game, Also check your CPU temperature and usage using MSI Afterburner; if it's reaching above 90%, your game will run poorly and there's a chance the game will get in slow motion (This is mainly in Conquest, Escalation or any map with extreme destruction, like Cairo) I say this because I'm having the same problem, but I've noticed that most people with this setup are running the game in dual channel and above 16gb ram, I also noticed that when my CPU reaches 90% or more, performance drops significantly, often increasing the TN latency, Firestorm/RedSec works normally, but Conquest and other large modes and extreme destruction maps are unplayable because of this."
Did you try a user.cfg with
Thread.ProcessorCount 4
Thread.MaxProcessorCount 4
Thread.MinFreeProcessorCount 0
Thread.JobThreadPriority 0
GstRender.Thread.MaxProcessorCount 8
just for testing?