Comment 34 for bug 1848534

So let me summarize your findings on the same host of yours (I suppose your VMs use the same config for the number of vCPUs and the memory size. I also suppose you only tested Hyper-V Generation 2 VMs or you confirmed Gen-1 vs. Gen-2 makes no difference):

("fast" means you can see the GUI desktop or the text terminal prompt in about 1~2 seconds, and "slow" means you need a much longer time, e.g. 1 minute (?))

fresh Server 19.10 ==> fast
fresh Server 19.10 + the ubuntu-desktop package ==> slow
fresh Desktop 19.10 ==> slow
fresh Desktop 19.04 ==> fast
fresh Desktop 19.04 upgraded to 19.10 ==> slow

So it looks a change in 19.10 with the xorg causes the slowness.

However, I can not reproduce the issue, because both my fresh 19.10 and 19.04 VMs boot up in 20+ seconds and I never have a boot-up time of 1~2 seconds.

Hi M, can you please check this case:

fresh Desktop 19.04 upgraded to 19.10 ==> slow

What if you boot the VM with the 19.04 kernel + 19.10's userspace (including Xorg)?
If it's also slow, then we have more confidence that the 19.04 Xorg has an issue.
If it's fast, then the issue may be more likely that the interaction between the 19.10 Xorg and the 19.10 kernel is causing the issue.

Can you also please try booting the VM with a "good" 19.04 VM but (ONLY) upgrading the kernel to 19.10?

In the slow cases, can you check the logs files (/var/log/Xorg*, /var/log/syslog*) and see if there is any obvious error/warning?