Question: How can I check to see if 

```
ob_start("ob_gzhandler");

```

is working and test the difference with or without it?

Thanks,

Answer: 
Using the "Net" tab of [Firebug](http://getfirebug.com/), check to see if the `Content-Encoding` header has a value of `gzip` or `deflate`.

Or, try the [online gzip test](http://www.gidnetwork.com/tools/gzip-test.php).

[See this question](https://stackoverflow.com/questions/2428542/how-can-i-verify-that-web-pages-are-being-gzipped).
You can use [`ob_list_handlers`](http://php.net/ob_list_handlers) to get an array of handlers that are in use.