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If your site only have 10000 monthly PVs, both are fine.
If your site will have 1 million of monthly PVs, Yii should be better at performance.
Otherwise if your site will have ten millions of monthly PVs, customize a framework from scratch.
If you're in a forum which content is highly related to your website, putting a signature under each of your posts/replies will generate many high quality traffic. It also help in SE ranking.