While YMMV, I've been running Ubuntu for years and have constantly had problems with flash. For me, freezes, crashes, and overall mediocre performance is not uncommon. And I think most Linux users who know about this subject can agree: performance of flash under Linux is much worse than under Windows.
This isn't a Linux problem or a Mac one, per se. It's an Adobe problem. And as long as Windows controls 90% of the market, Adobe has no real incentive to cater to the needs of minority OSes. Let's look at the facts; that flash is a closed source format which only Adobe can tweak to improve or modify. Which means we are at there mercy if there are any problems.
Let's look past the fact that Steve Jobs is a very rich man, and that it's the in thing to criticize such people. Or that Apple is one of the success stories of the last decade, much to the chagrin of "normal" computer folk. Flash is a resource-hungry, bloated program, created by a company that has no reason whatsoever to improve its performance.
A move to an open standard would be by far the best solution for everyone, regardless of the OS they use.
With that said, VGChartz is one of the most flash-heavy sites that I browse, and with flash enabled, it usually slows to a crawl. I usually use a flash-blocker when I can. If possible, switching to HTML5 would be fantastic.