bitflipper
I used a generic off-the-shelf i7 laptop with 8 GB of RAM. It's just what I already had, and it started out as just an experiment. I didn't know if I'd need an external interface or if the integrated audio would be OK.

That’s a problem with Windows laptops, you can never be certain that any particular one will give low latency figures. At least, not unless it comes from someone who understands DAWs and can certify it will work. Even with a good external interface PCI bus interrupts or BIOS settings you can’t get at or change can cause problems.

Which is one reason why MacBooks turn up on stages far more often than Windows laptops. Another is Apple’s control over the components and operating system plus stuff like built-in native MIDI networking over wi-fi, which you can use without it causing dpc issues. And, as has been said, Mainstage is another reason.

Dave,
Go to moltenmusictechnology.com and select the u-tube menu.  The author tests the Surface Pro 4, Surface Book, and Surface Pro 2017. He likes the touch screen.  If not interested in these laptops at least you have an idea of what their components will do.  At the very least, watch the videos on how to set up a laptop for audio.  This may relieve some of your anxieties about dealing with the Windows OS.

When I grow up, I'm gonna get a surface pro.

I just keep using my USB ssd with Ubuntu studio on it.

I'd love to have touch and sonar on a laptop at a performance. I think I'm waiting for the rapture threading magic that will make it safe for stage use for a guitarist.

Right now, it is fun at home, but not solid enough for the stage imho.

Specifically, when I play, I have to watch the processor and when it gets hot, back off.

Good suggestions all around. Currently, when I do a solo gig and duo's I use my iPad pro. The issue is that the samples are not as extensive or as powerful as those I use for Kontakt, etc. Not a big issue for some situations. A mac Mini would be great, but it has no screen, so a laptop is probably the better way to go, preferably with enough hard drive space to load samples and quickly, too. Gonna check out the videos suggested, too.

A touch screen lappy may make it easier too. Sort of gives you that iPad flexibility with the power of a laptop. I remember the times I went out to play with a lap top which were few and far in between. If using midi though I guess it doesn't matter as much. Can you tell I wouldn't mind having  touch screen laptop? 

Save time and money. I leave my studio stuff at home and mix all my tracks to audio files. That way just about anything will work for playback. I use an iPad and my phone is my backup. Mix them through one of your PA speakers and they will sound fine.

Save time, money and grief. I leave my studio stuff at home and mix all my tracks to audio files. That way just about anything will work for playback. I use an iPad and my phone is my backup. Mix them through one of your PA speakers and they will sound great.