Yii framework scalability

I'm a starter in yii framework. I just want know how scalable Yii is with a lot of online users at a time?

How useful is Yii in comparison to other frameworks and also if there are 100,000 users - to have things move smoothl开发者_开发问答y - what kind of technology and hosting etc would be needed?

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This article compares Yii and Drupal on a website with more than 50000 visitors per day. http://erickennedy.org/Drupal-7-Reasons-to-Switch

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100,000 users is a bit vague. Is that per minute, per hour or day? Yii does have a good caching functionality but perhaps worth reading Building Scalable Web Sites: Building, Scaling, and Optimizing the Next Generation of Web Applications by Cal Henderson, as this will give a better understand of scaling PHP web applications.