Ciao Claudio,
I also restart the Pentaho context when I update the component.xml... so I can't help with that.
However, I suggest you to edit pentaho-solutions/system/pentaho-cdf-dd/plugin.xml in this way when you develop a new component:
Code:
...
<operations>
<operation>
<id>RUN</id>
<command>content/pentaho-cdf-dd/Render?solution={solution}&path={path}&file={name}&debug=true</command>
</operation>
<operation>
<id>NEWWINDOW</id>
<command>content/pentaho-cdf-dd/Render?solution={solution}&path={path}&file={name}&debug=true</command>
</operation>
<operation>
<id>EDIT</id>
<command>content/pentaho-cdf-dd/Edit?solution={solution}&path={path}&file={name}&debug=true</command>
</operation>
</operations>
...
Using the debug mode, CDF won't create the minified version of your component's javascript files. So you don't have to restart Pentaho when you update them. However you will probably refresh your browser cache.