Hi..
My brother want to learn Arduino and I want to buy him a laptop. Which Performance is best for arduino Programming?
You should be aware that the standard Arduino IDE is not compatible with Chrome OS. There are a couple of options for making it work but they might be a little advanced for a beginner. You also have the option of purchasing the Arduino Create app for $1/month and using the Arduino Web Editor. So I'm not so much recommending against a Chromebook as making sure you're aware of the implications in advance.