I know this, because I also use a netbook.
Actually no you don't because you don't know his specs. He could easily be running minecraft with 512mb of RAM which would have poor performance
constantly, not just when loading chunks.
It could also be an issue that his system is sufficiently powerful but his components are overheating due to a clogged heatsink.
That's like saying that a $1,500 laptop and a $750 laptop are identical because they are both laptops.