Signal Boost! I'm having this exact same issue. After joining the 7DTD server, the game is a slide show, even at its lowest quality. BUT, I have this system setup with bootcamp with Windows 10 running on the other partition. If I boot into Windows 10, the game plays like a dream on the same hardware specs. I'd prefer to play this game on the Mac side for other reasons, but it's unusable. Hardware specs below:
Model Name: iMac
Model Identifier: iMac14,2
Processor Name: Quad-Core Intel Core i7
Processor Speed: 3.5 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Hyper-Threading Technology: Enabled
Memory: 32 GB
Boot ROM Version: 146.0.0.0.0
SMC Version (system): 2.15f7
Storage:
Samsung SSD 860 EVO 4TB:
Capacity: 4 TB (4,000,787,030,016 bytes)
Model: Samsung SSD 860 EVO 4TB
Revision: RVT04B6Q
Any info on this would be appreciated.