使用APC（最新版本/最新）时，自动加载是否真的会扼杀性能。基准？

就个人而言，我不认为依赖__autoload（）是很好的做法。PHP是一种松散类型的语言，而不是懒惰类型的语言。:)

在这里查看一些性能：

• http://weierophinney.net/matthew/archives/245-Autoloading-Benchmarks.html
• http://www.ilia.ws/files/zend_performance.pdf

Rasmus对此的回答（你也发现了）是我这些年来的指导线：

<arnaud_> does autoload have a performance impact when using apc ?
<Rasmus_> it is slow both with and without apc
<Rasmus_> but yes, moreso with apc because anything that is autoloaded is pushed down into the executor
<Rasmus_> so nothing can be cached
<Rasmus_> the script itself is cached of course, but no functions or classes
<Rasmus_> Well, there is no way around that
<Rasmus_> autoload is runtime dependent
<Rasmus_> we have no idea if any autoloaded class should be loaded until the script is executed
<Rasmus_> top-level clean deps would speed things up a lot
<Rasmus_> it's not just autoload
<Rasmus_> it is any sort of class or function declaration that depends on some runtime context
<Rasmus_> if(cond) function foo...
<Rasmus_> if(cond) include file
<Rasmus_> where file has functions and classes 
<Rasmus_> or heaven forbid: function foo() { class bar { } }

我做了更多的谷歌搜索，发现这篇有趣的文章总结如下：

针对每个策略运行了 10 次基准测试：

结论

每种方法都有其优点。在开发过程中，您不希望每次添加新类时都运行脚本来生成类映射或手动更新类映射。也就是说，如果您期望站点获得大量流量，那么在部署期间运行脚本来为您构建类映射非常容易，从而让您从应用程序中获得一些额外的性能。