DTL VM becomes laggy / slower in afternoon and evening

Question

I'm connecting to a DTL VM, recently more than usual, and I'm experiencing a change in performance as the day progresses.
I'm temporarily working from the Eastern Time zone, so today around 4:30pm ET (1:30pm PT) my VM suddenly became slow to respond to mouse-clicks, etc.
Last night (~10pm ET, 7pm PT), my machine was basically unusable it was so slow.
This morning, the machine was fine, as if it were my local client.

My question is, is there a known explanation, and how can I diagnose the problem when it occurs?
Some thoughts:

1. Given this lab is on West US 2, and I'm on the US East Coast right now, maybe during heavy usage times the physical distance causes problems only for me.
2. Perhaps the shared server/pool where my VM resides gets busier later in the day, and that manifests as lag/slowness on my VM.
3. Local networks are usually busier in the evenings, so maybe the bottleneck is on my side.

Answer 1

Is there a known explanation?
On average, network speed between Azure regions is pretty fast (roughly 65ms for US West2 and the East US, for example). When making a local connection using Remote Desktop, however, you'll typically encounter increased latency due to load during peak hours depending on your service provider and location. It sounds like the evening are peak hours for your area with heavy traffic.

How can I diagnose the problem?
A quick resource for checking latency is http://azurespeedtest.azurewebsites.net/, which measures speed from your browser to blob storage services in different data centers (remember that this includes local network latency).

If you suspect that some of the latency is due to heavy Azure datacenter traffic, there are tools you can use to test your VM's network latency:
https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-test-latency

What can I do to improve latency in Labs while using Remote Desktop?
I would create a lab in a local region as long as there aren't hardware limitations. Shared image galleries make it easier to globally replicate images in different regions:

https://learn.microsoft.com/en-us/azure/devtest-labs/configure-shared-image-gallery