Had this issue back on Windows 7 with the official servers too. My PC is pretty beast, can stream modern games like Overwatch on max settings, so I doubt its a hardware issue. I'm running Windows 10 now.
Basically, the game can sometimes freeze on a frame for a second then will continue as normal.
It happens at random, whether in combat or walking around.
I was able to record it happening, actually;
So yeah, had this happen back when the official servers were still up but I assumed it was my weak Laptop. Now I have a pretty powerful PC, and I still have this issue. Was wondering if anyone knew a fix, or if it was just the way the game was made.
CPU
Intel Core i5 4690K @ 3.50GHz 61 °C
Haswell 22nm Technology
RAM
16.0GB Dual-Channel DDR3 @ 799MHz (10-10-10-30)
Motherboard
ASUSTeK COMPUTER INC. Z97-A (SOCKET 1150) 28 °C
Graphics
Generic Non-PnP Monitor (1920x1080@30Hz)
DELL E176FP (1280x1024@60Hz)
NVIDIA GeForce GTX 970 (NVIDIA) 48 °C
Storage
931GB Western Digital WDC WD1003FZEX-00MK2A0 (SATA) 26 °C