Large difference in results between London and Dublin

I was wondering if anyone could shed some light on why I would be getting such different results between the London and Dublin locations.

I completely appreciate that location would be expected to make a difference. But I didn’t expect to see as much difference as I’m seeing given these are Geographically close together.

Some background:

[]The server hosting the page being tested is in London
]Static assets are being hosted via CloudFront backed by an S3 bucket in Dublin
[*] Tests are both on Cable w/ 3 tests each

SpeedIndex of 2148 on first run

SpeedIndex of 928 First Run

Anyone know why these results would be so different?


Geographic location and network paths on the Internet are not always closely related.

I’d suspect that the bandwidth between your server and London is significantly different between your server and Dublin.

More likely is that the London node is also running on slower hardware/VM than Dublin. Unfortunately there’s no guarantee of hardware consistency from location to location with the public WPT agents.

Things shouldn’t be nearly that bad though so I’ll see if there’s anything going on with the London test agents.