Same issue for a year now with watching Flash content, nothing has changed

Question

One of my main gripes about Safari, is that while I am watching a flash movie in one safari window and have another safari window open typing, doing work etc., the flash video stutters in the first window (looks like it is evenly dropping frames incrementally) . Sound is fine, no prob there.
It doesn't matter what flash video it is, from whatever site, it will always do this... and it is very annoying. When using Safari, do I really have to be using one open window, while watching the Falsh content so it is smooth like it was designed to be?
Now on the other hand i do not have this problem in Firefox. I can have two windows open, one playing flash content and I will have it sized down in the left hand corner of my screen, and have another window open which I am typing in, and have no reduciton in quality...whatsoever.
I have tried everything possible, I am not a new mac user , and I am familiar with every suggestion one would suggest here as a starting point. Regarding, Permissions, trashing folders, resarting, re-installing combo updates, un-installing flash, re-installing flash; etc, etc.
Thanks

Answer 1

Thanks for the the speedy reply. And thank you for all your suggestions about standard plugins and the current plugins now available to the user. I am familiar with them, etc. i have also restarted,
"repaired premissions" etc. Yes, I am current in OS, Flash, all plugins you speak of, etc. Combo update has been re-applied, flash un-installed, then re-installed...etc, etc..
I have attemped everything you speak of, and everything I can come up with, but there is no change in my problem.
Can you do something for me? I want you to go onto the youtube website, pick a video to watch and and with only one safari window open, I want you to leave some room on top of browser window so you can see your desktop. Now move your cursor over your desktop, and click on the desktop - which will activate the finder, and Safari will no longer be the chosen app. Do you see the difference in picture quality in the safari window hosting the flash video?
Try it again. Click on the Safari window, then back to the desktop. Vice versa. Everyone I know I have showed this too , sees the obvious difference. My mother says, well I can see what you are talking about, but it doesn't bother me...well, my mother is pretty old, so she doesn't count.
Well, for me The picture quality starts to drop frames evenly through the whole entire video.
Firefox does not do this.
Can anybody else try this,
my system cannot be the casue,
for I have recently re-installed this OS,
and the problem still exists. I am very familiar with updates,
and the like. All the usual suggestions have been applied.
And, If this is just the way it is in Safari, I can live with that...I mean, i live with the memory leaks that it has, and other quirks about it. But, If this is a unique problem , then ..well, I have a problem