`az deployment ...` very slow compared to times reported in portal

**Describe the bug**
When deploying ARM Templates using the `az deployment ...` series of commands the time spent by the command is much longer than the reported time deploying by the portal.

**To Reproduce**
Deploy some ARM templates using `az deployment` commands (`sub` and `group` for example) and check how long the `az` command takes to terminate vs the times shown in the portal.

**Expected behavior**
`az` should return quicker if the portal reports much lower times.

**Environment summary**
N/A

**Additional context**
Here is the time spent while deploying a Resource Group and Role Definition (which already exist):

This is how long it takes to provision the templates using two parallel `az deployment sub` commands in an Azure Pipeline:

(The reason I now run some of the ARM commands in parallel is because they all take ~30 seconds even if there's no changes made to any infrastructure...)

Thinking further this may not be the right place to raise this (as `AzureResourceManagerTemplateDeployment@3` is also just as slow which is why I started to parallelise them using Pwsh and `az`), but I can't think of where else this should be raised and so here is a start and maybe we can at least get a discussion going or a pointer to another place to report this. Thanks.