Hello

Is it possible to use Nginx as front end of Apache and xcache under Suphp?

Thank you

Sure, i am using this.
Nginx (frontend) for statics, apache (backend) with suphp and eaccelerator. You can do this with every PHP application.

You will have best performance with litespeed webserver (but it cost money, 15 days trial is free) or nginx alone.
Litespeed also is working with suphp etc. and can handle .htaccess.

For eaccelerator it works but it will work with xcache under suphp?

Thank you

xcache 1.2.x doesn't work under suphp, xcache 1.3.x I haven't tried yet.

But like I said in other post you really need to optimize apache and mysql before you make switch to nginx or litespeed.
If you have any questions regarding Litespeed just let me know, I use it on few of my sites.