Optimize results

Hello,

I am trying to speed up the results I got while performing a
transformation with XML and XSL files (PHP, Sablotron and XML - XSL
files).

Some questions...

- What are the steps to get a lightweight transformation? 
- What to check in XSL file?
- Is there any way to make a "Loading data, please wait..."
instruction while Sablotron is working?

Any tip to accelerate the load process is highly appreciated.

Greetings.