Triton and SmartOS are still Sun Microsystems people. Solaris zones preceded Linux containers by almost a decade. They lost the popularity contest, so they have to provide compatibility with kube and docker. I think infrastructure containers are zones with extra whistles.
For even better performance, I'd go with Xen and Linux unikernel. The startup time can be just 1s with such minimum overhead. It also greatly reduces the attack surface. I highly doubt you'll be allowed for such a drastic change though.