How well does CS run on Mac?

I've played it on my Macbook Pro for about an hour or two. I believe I have a 2013 model. I can't remember noticing any lag or anything.

I believe that all source games are optimised to work on MacOS just fine. As long as your specs can handle it (which it most likely can if you're running one of the newer models). You should be fine.

my macbook air 13" 1.6ghz (i think) is running csgo at 30-50 fps so it can run pretty good

It depends on the system itself. If it doesn't run well in the first place, don't expect miracles to happen. It doesn't take much to run Source Engine games these days, though.

I dont really think that you should play games on macbook, it more like expensive shid for surfing sites.

I used to have a mac, if you turn the settings all the way down, you should get a solid 60-80 fps