You don't lose much performance with kvm, in fact; you lose practically none, and that's full system virtualization with the possibility of passthrough, for instance of network devices or graphics cards.
A chroot-ish application like Docker or lxc doesn't have the same goal or application area as kvm/qemu or any of the more commercial type I or type I-ish hypervizors (Xen, VMWare, etc...) or any of the dozens of open source type I and type II hypervizors. You'll never be able to use Docker instead of a full virtual machine, because it serves a different purpose.
Docker is very much usable and ready for what it has to do in the enterprise world, which is the main market for Docker, but there is a world of extra possibilities for virtualization technology, some of which will be explored by Docker, some of which will only be explored by other projects.
The advantage of Docker is that it is well supported by the enterprise world. It's not the most comprehensive or the best performing project of its kind. That is just what often happens because of marketing and politics. You want kvm but you have to use VMWare or Xen because nobody wants to write tools for kvm management because it's too open source for their taste. You want sandstorm but you have to use Docker because of the same reason. That is not a new problem, that is life, it's like getting drafted and they give you a Colt M4 instead of a HK416 or a SCAR, the standardized tool is not always the best, in fact, it might very well be the worst.
Just use the tool that suits your requirements the best. In Linux, you're really spoiled when it comes to tools in general, and tools for virtualization in particular. You want to virtualize for games, so you need performance right? And you have an nVidia GPU, so you don't have the option of using open source drivers for games. Those two use case conditions make that kvm is the best solution for you, because you can have easy PCI passthrough (and don't worry about Bumblebee, it's only purpose is to save battery power, saving battery power and gaming at the same time is not an option anyway), and because kvm lets you run a virtual machine faster than it would run on bare metal. Only kvm/qemu can do that, only kvm/qemu offers a performance level that is way higher than any other type I hypervizor or virtual environment application. Kvm on a bleeding edge RPM-distro is at least 20% faster than Xen, which is the runner up in terms of performance.
If it's just for Linux native games, and for instance the Steam client for Linux, and you can use KMS GPU drivers (which on nVidia isn't very likely), lxc is the best solution, because again, the performance is way better than anything else like it, and it works out of the box. There is no sandstorm or docker support for the steam client, and there will never be. However, lxc doesn't require support by the application, it always just works. Lxc uses the very same virtualization technology as docker, and is quickly evolving towards using all the virtualization functionality offered by the latest Linux kernels, which is currently only used by sandstorm and chromium, but in the future, will also be used by docker and of course lxc (and lxc will probably evolve much faster than docker, because docker doesn't have to evolve fast, because the enterprise market, which is targeted by docker, is mainly still on the ancient kernel 3.2, because that's a kernel that they can have in a hardened version out of the box, without actually having to pay a guy that knows how to harden a kernel, and that's the kernel used by a distro that they can have configured out of the box, without having to pay a guy that actually knows how to set up and properly maintain a bleeding edge linux environment, so by the time the enterprise world is on kernel 3.17 and can actually use the technology that is now being used by chromium and sandstorm, it's the year 2016/2017, so docker still has about 18 months to catch up, and that's an eternity in open source...)
Bumblebee is dependent on two GPU adapters, one iGPU by Intel, and one nVidia mobile. If you don't have those two adapters running on the same system, there is no chance of getting it to work properly, and even if you have both of these on the same system, most of the time it doesn't work properly, well... because nVidia and Intel don't always offer a problem-free experience on Linux, nVidia because they hate open source and are evil mentally retarded, and Intel because they can't get their open source-only drivers quite right because they've fired all of their (100+) graphics drivers developers in the US because they weren't performing well enough, and they moved the whole driver development program over to China, where they only have a very small low budget team, that has only been working on the drivers for about a year now, during which time Intel has made them do a lot of development-from-absolutely-scratch for Atom-core stuff and for OpenCL development, where Intel has a couple of years of development to catch up.