I played about 40 minutes last night with a 3570k at 4.4GHz, and I saw framerate drops down to ~40-45fps in 64 player multiplayer matches. This was at 1080p ultra with 100% scaling, but I tried dropping settings and it wasn't making a difference, it was all cpu bottleneck, my 980ti was hovering around 60% utilization.
I didn't get to test DX12 to see if I noticed an improvement, I will be doing that tonight. The SP portions were just fine at locked 60 with a bit of breathing room, and I did not try a smaller lobby to see how improvements were with less people.
Not surprising. Battlefield 3 and 4 with a full server on larger scale maps could hammer a 2600k@4.7Ghz with 70-90% usage and a 2500k or non-HT 2600k would be at a constant 100% CPU usage with terrible and unplayable performance.
This is why I chose not to waste my money in 2010 on a non-HT CPU since I knew there would occasionally be a game that comes along that needs the extra breathing room HT provided.
I was laughed at for spending the extra $100 and that a 2500k was the way to go, but the ones laughing, I had to hold back snickering when I saw them forced to upgrade their 2500k's to either the 3770k/4770k while I was still sitting perfectly fine until affordable 6c/12t CPUs came out.
Non-HT CPU's with gaming intentions have been a waste of money for going on half a decade now.