This is more of a warning than a tip. Remember when iPhoto was freely downloadable? That was iPhoto 1 and 2. Running iPhoto 2 under Tiger writes the following warning to /private/var/log/system.log:
Applications/iPhoto.app/Contents/MacOS/iPhoto: The function CGSDictionarySetObjectForKey is obsolete and will be removed in a Tiger update. Unfortunately, this app, or a library it uses, is using this obsolete function, and is thereby contributing to an overall degradation of system performance.The message is repeated for five other functions in iPhoto 2.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050629000756524