A friend of mine was over the other day and I was showing him this cool website I had recently heard of, grooveshark. So after admiring it for a little while he came out with "pity it's written in flash". So of course I asked the obvious question "Why?" and got the obvious answer "Because it's inefficient and sucking up all your CPU". He popped open 'top' and sure enough it was using 35% of my cpu, his point was proven.
However, that is completely and utterly irrelevant. This does not make flash a bad technology nor does it make grooveshark a badly written application. Maybe 35% cpu usage is just the cost of running in the browser. It's like the old complaint against firefox, "Firefox uses too much memory". By itself that means absolutely nothing. It's nonsense. For that to have any real meaning you'd have to compare firefox to another browser doing the same task. A legitimate complaint might be "Firefox uses 3 times more memory than opera when I view www.example.com, 300 mb versus 100mb". An arbitrary decision as to what amounts to be "too much" is useless without a reference. This is exactly what far too many people are doing to flash.
Sure, grooveshark uses more CPU and memory than banshee, but banshee isn't running inside firefox. It annoys me that people make such arbitrary decisions and try to pass off as fact that flash is inherently bad and HTML5 is inherently so much better and yet have no reference to compare against. I haven't seen anything even close to the complexity of grooveshark written using html5. So before you get on your high horse decrying all plugins, show me a comparable application which uses $COMPETING_TECHNOLOGY_OF_CHOICE and performs measurably better.