Suspend VERY slow on 19.10

I have an HTPC that on 16.04 used to take about 5-10s to suspend: just long enough for me to put my glasses away etc before the TV went dark. When I ran 18.04 for a few days, that dropped to about 1-4s: often fast enough to almost be an issue for me!

On 19.10 though, it's usually more than 30s - often WAY more. Obviously nothing has changed with the hardware etc: it's just suddenly become ridiculously slow. Has anyone else run into this and/or found a solution to it?
(To be clear, IDK if the bug first appeared in 18.10 or 19.04 rather than 19.10 - I skipped over those).

Finally shut down the 19.10 VM I've been running, and I see that shutdown is also ridiculously slow.

What's interesting is that that VM's on an HDD rather than SSD, so I can tell that it's simply doing "nothing" at all for 20-something seconds. And that's on a Xeon, not a relatively-low performance Celeron like the HTPC (although even that realistically has plenty of CPU for something so trivial, and was fine prior to 19.10 as mentioned).

That's convenient, since it'll be a lot easier to debug on the VM. It also removes any possibility of it being hardware-related, and puts the bug firmly in 19.10's software, so I'm surprised I haven't seen any mention of it already. I'll try to dig into it over the weekend.

This magically "fixed itself" a week or so ago, with both of them now suspending or shutting down within 2-3 seconds. I'm going to assume it was just a defect in the pre-release builds and ignore it.