Yes dual GPU. I set that up like 6 years ago, so its use changed over time. It used to be Windows but now it's another Linux VM.

The reason I still use it is it serves as a second seat and is very convenient at that. The GPU's output is connected to the TV, so the TV gets its own dedicated and independent OS. So my wife can use it when I'm not. When the VM isn't running I use the card as a render offload, so games get the full power of the better card as well.

I also use it for toying with macOS and Windows because both of those are basically unusable without some form of 3D acceleration. For Windows I use Looking Glass which makes it feel pretty native performance. I don't play games in it anymore but I still need to run Visual Studio to build the Windows exes for some projects.

This week I also used the second card to test out stuff on Bazzite because one if my friends finally made the switch and I need to be able to test things out in it as I have no fucking clue how uBlue works.

Yeah it'll depend on how good your coreboot implementation is. AFAIK it's pretty good on Chromebooks because Google whereas a corebooted ThinkPad might have some downsides to it.

The slowdowns I would attribute to likely bad power management, because ultimately the code runs on the CPU with no involvement with the BIOS unless you call into it, which should be very little.

Looking up the article seems to confirm:

The main reason it seems for the Dasharo firmware offering lower performance at times was the Core i5 12400 being tested never exceeded a maximum peak frequency of 4.0GHz while the proprietary BIOS successfully hit the 4.4GHz maximum turbo frequency of the i5-12400. Meanwhile the Dasharo firmware never led to the i5-12400 clocking down to 600MHz on all cores as a minimum frequency during idle but there was a ~974MHz.

I'd expect System76 laptops to have a smaller performance gap if any since it's a first-party implementation and it's in their interest for that stuff to work properly. But I don't have coreboot computers so I can't validate, that's all assumptions.

That said for a 5% performance loss, I'd say it counts as viable. My games VM has a similar hit vs native. I've been gaming on Linux well before Proton and Steam and have taken much larger performance hits before just to avoid closing all my work to reboot for break time games.

As far as I know it's also less documented. People have dug really deep into Intel ME that they even found a bit that disables most of the ME.

On the other hand AMD is planning to use coreboot compatible open firmware in the next EPYC generation. Knowing AMD, it will eventually come to the consumer market too. (We'll see if it will be available before Red Hat drops x11)

Also there was a phoronix article recently that Intel is too messing around with Coreboot on Xeon.

passive/active are just 2 modes you can select between and active is simply better so for me there's literally 0 problems