Since I usually arrive smack in the middle of the AM rush on either CX or BR, I also get to see all the flights from Russia and the 'stans in line with me. In my observation, I do notice that U.S., Canada and Japanese passport holders get through the quickest, followed by Russia and then China.

In my experience, it always takes me a couple of extra minutes though since I have a visa, and the agent looks at all the pages except for the actual visa page that is marked with a paper clip for the visa itself.