Ever since Microsoft and Qualcomm announced in December 2016 that full Windows 10 would be coming to ARM processors, the question on everyone's mind has been how well those x86 apps will run. After all, we all know that legacy Win32 apps don't perform well and drain more power than UWP apps, but since they'll be run with emulation, one would assume that the cost would be even greater.
I got a chance to talk with a representative from Qualcomm, Pj Jacobowitz, at CES last week, and the answer is that it won't. I was told that the performance and battery life impact should be the same as it would be on a PC with an Intel processor.
All of the Qualcomm-based PCs that have been announced promise up to 20 hours of active usage, at the least. We won't see these new PCs until the spring though, and I don't have one to review yet (*cough* I'm looking at you ASUS, HP, and Lenovo), so I won't be able to do my own tests until then.