I am answering my own question, because no-one has the courage in this forum to advise me.
Flash CS4 is terrible at editing ActionScript. It has no code hinting and its lack of performance spirals the user into a torpor.
it is almost like buying a Ford KA because the specs say that its top speed is 75mph. So you take it on the freeway, but it takes 20 minutes to get up to 70 on the flat. You call Ford up and the very sweet lady tells you that you are better off with a Taurus just for the freeway stretches. Ok then. I'll take one of those too.
I love Adobe. Don't get me wrong. In a fight with Apple. I will back Adobe everytime.I go back years with these products. I know that Adobe is trying to fix these ills in Flash. I have seen the CS5 feature peeks.
I just hope that Adobe will be kind to loyal users in the upgrade path with regard to Flash Builder 4
it's always smart to insult people from whom you're seeking help.
Flash CS4 was super slow for me on my office win 7 machine. After a few days' of struggle, it turned out to be some corrupted fonts. I tried the "Reset default font settings" in Win 7, and also moving all fonts out and putting them back in (didn't test to see which worked.) Now Flash is working decently.
After 3 years this thread emerges from the Grave. Happy Birthday.
I was just trying to help others who might be as miserable as I was... I didn't find anything helpful around, but fortunately remembered doing the same thing a few years back. I do work on Chinese characters a lot.