I Agree developing  portlet with liferay  is a very time consuming process.but there are some semi solutions  to decrease amount of waste of time. for example :

1- how do you deploy your portlet?

2- dont restart your tomcat every time you change your code.
you can re-add your portlet. see admin panel of your tomcat or life-ray.

3-you can set your debug port to your IDE ,so that you can debug from within IDE. I use JBuilder . I am not so happy with it but at least it works.

4 - most of the debuging headechs come from xml files . so you can write a tool to automate management of youe web.xml,struts.xml,life-ray.xmls and so on.
although some IDEs have such tools.

5- sometime you must debug like blinds. there might be no sign of the root of your bug.but you can trim your newly added part of your code and see what happens. it is not a good practice at all but sometimes is necessary.