I am having the same issue of the game suddenly freezing after a few minutes of being logged in. My screen goes black and I can’t tab out of GW2. I have an iMac as below details. This has just started happening today.
Model Name: iMac
Model Identifier: iMac12,1
Processor Name: Intel Core i5
Processor Speed: 2.7 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 4 GB