[Mac] Severe fps dropping;

Since the latest build arrived, i've been experiencing extreme fps drops to the point where my game freezes for up to 5-10 seconds at a time. This is using both OpenGL and Metal graphics API

Model Name: iMac
Model Identifier: iMac13,2
Processor Name: Intel Core i7
Processor Speed: 3.4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 8 GB
Boot ROM Version: IM131.010A.B09
SMC Version (system): 2.11f16

Chipset Model: NVIDIA GeForce GTX 680MX
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 2048 MB

there's some hardware info, and here's my actual graphics settings ingame for beta.

http://imgur.com/a/gH9Mt