Yufang has an Early 2008 white Macbook, which we upgraded to Snow Leopard last year. Since adding 64bit software to her daily processing, she’s had to deal with a lot of loud fan revving and droning while using Safari and Adobe Flash Player. Tonight, I finally thought of a solution that, so far, seems to have done the trick. Up to this point, I have tried everything short of a nuke-and-pave reinstall of MacOS X, including: installing all Apple updates, continually updating Flash, repairing disk permissions, and resetting the SMC. Tonight, I was watching what was going on in Activity Monitor, and I thought about the fact that Safari runs in 64bit mode by default and Adobe Flash is still 32bit software on MacOS X. I wondered what would happen if I launched Safari in 32bit mode and tried loading up some Flash videos. Eureka! Now, Flash isn’t identified as running in Activity Monitor, and I assume is running within the Safari process (or via some kind of process reporting magic). Whatever the case, it seems that if you are experiencing this same problem on a MacBook (probably due to its lack of a real GPU), you can resolve this problem by running Safari 4 in 32bit mode: Select the Safari icon in the Applications folder > File > Get Info > Check “Open in 32bit Mode” > Close window > Relaunch Safari. Good luck, and please comment if you have other ideas or if this doesn’t fix your problem.