Unplayable lag - Does not appear to be networking issue

I appear to have a bug that is causing unplayable lag.

Is there any way I can help further diagnose this problem?

As I have recorded in this video:

[Removed by Support]

Just sitting in town, I get constant lag spiking, and it's unpayable.

But pinging the exact same game instance, at the same time, I appear to get a smooth ping. Nearly all 12-16ms, with only a single spike to 20ms. Not a single packet lost.

So something else is happening, what can I do to further diagnose the issue?

Is it CPU / network stack related? Is there any way I can pseudo-ping via UDP to better mimic the game and measure that?

Is it just the game server failing to keep up and therefore not send updates to the player?

It's extremely frustrating, I'd just like to enjoy PoE again.