That seems unlikely. For an accelerated tab you'll have the Tab process, the GPU process, and the Browser process. Even if you pegged all three (which is extremely unlikely considering the content), you'd still have a core to spare.

There's a point in there about the relative maturity of graphics code, but let's keep things honest (also, I think the Mac/Windows divide on Flash would be lessened if everyone had to use Flash on the other platform for a while. Imagine your CPU doing that on virtually every page that decides to embed a Flash ad and you'll get some idea of what it's like on a Mac).

Yet it ran fine on my single core two year old netbook on Firefox/Linux, while Flash rarely does.

Of course, Flash on Linux is even worse than on Windows.

Must be a Windows or Chrome problem. On my dual core 3-year-old Mac, Safari stayed between 20 and 30%.

Sounds like what Flash does on linux or OSX, 1:1 perfect replacement!