I have a question. How does Yii perform compared to Prado 3, Seagull or Zend Framework, for instance? Do you have some profiling or benchmark?
I know this kind of benchmarks are most of the time hated because there are several aspects which affect the performance, but I'd like to have some basis for deciding to switch to Yii for new developments.
Thanks 
Yes, performance is affected by many factors. The one shows on this project website mainly reveals the minimal overhead caused by a framework. This time is crucial because there is no way to avoid it unless the framework is optimized or some server caching technique is used.
The comparison already shows Yii vs. Prado 3. I just profiled Zend framework and the result is very poor: 22 RPS without APC and 14 RPS with APC (this is very interesting, it seems Zend doesn't go well with APC. I repeated the test several times and got similar results.)
I didn't compare Yii with Seagull mainly because Seagull doesn't come with a suitable demo and there are a lot of STRICT PHP notices.
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I know this kind of benchmarks are most of the time hated because there are several aspects which affect the performance, but I'd like to have some basis for deciding to switch to Yii for new developments.
Thanks
For some quick numbers, see http://www.yiiframew…om/performance/ 
From the diagram you see that without APC "standard" Yii is faster than yiilite. How comes that?
This is because yiilite.php is a file with 163KB. Parsing this big file takes significant time. When APC is enabled, this time is saved.
Question: Why is codeigniter v 1.5.4 used while 1.6.3 is the 'current' version ?
I just updated the results by replacing CI with 1.6.3 version. Thanks for suggestion.
Where is the source for the comparisons?
Per your request, I just compiled together the testing scripts. Please download it at http://code.google.com/p/phpmark/