Why do Hulu videos run great on a 2009 Macbook Pro, but suck on my 1-week-old Macbook?

I just bought a new Macbook pro.  I've installed the latest version of flash player, and streaming videos are jumpy and jerky.  It's subtle (my wife has a hard time noticing it), but it is there.  It's much more noticeable when I play the same video side-by-side on our old Macbook...

Meanwhile, our 2009 Macbook pro plays videos very well.  It's such a dinosaur that we can't even update the flash player or the web browsers anymore.

The new Macbook is running OSX 10.9.3 (Maverick, IIRC), and flash was installed yesterday (version 14.0.0.125).  The jerky video play happens in both Safari and Firefox.

The old Macbook is running OSX 10.5.8 (Leopard), and Flash 10.3.183.15

So, how can I make my new computer work "right?"