The response time from your VPN server to the game server doesn't account for all the overhead and processing that takes place when the VPN routes traffic to your computer and back, so that is probably why there is a delay.
Also just curious, why are you playing through a VPN?
Since beta I have been experiencing graphical stuttering approx. every 3-4 minutes while in a match. It seems to happen less if i've been playing longer in a single sitting but I have no data to back this up. It seems to happen mostly when rounding a corner, or walking outside after being inside a building.
I can watch the performance of my computer on a second screen while this is happening and none of my resources are every close to being at 100%. I do notice that while the stuttering is happening my GPU utilization will drop to 0%. The stuttering last a couple of seconds and then returns to normal.
I have experimented with a variety of graphical settings with no effect. Currently I have it set to "Auto". I have also disabled steam overlay and am playing the game in full-screen. The game is running off of a SSD.
CPU: i5 2500K
GPU: GTX 780
If I can provide any other information please let me know. I really love this game when it's running normally!