Flash is a heavy software when you have unoptimised content. If designers take some time optimising them, it's not heavy at all. The problem is that most advertisers just care for it done as quick as possible and with bells and whistles flying all over the place. I've been developing with flash for a long time now and there's no netbook crashing with my content.
Adobe is taking more time than it should to optimise the whole engine but that's the price you pay when your software is grown to something bigger than what it was designed for in the beginning.
Yes, everything you can do in flash can be done with html+css+javascript and you can even add it java. The difference is that you need a designers team working in collaboration with a developers team for something you could do in an hour and another hour optimising.
Adobe is taking more time than it should to optimise the whole engine but that's the price you pay when your software is grown to something bigger than what it was designed for in the beginning.
Yes, everything you can do in flash can be done with html+css+javascript and you can even add it java. The difference is that you need a designers team working in collaboration with a developers team for something you could do in an hour and another hour optimising.