The tostring generation tool in netbeans is very basic and used String object to append. This is a very memory consuming thing and you wouldn’t want to use if your POJO class has many members. ( remember your first java lesson: String concatenation produces a new String object everytime ).
I found Simon Martinelli’s plugin which gives you an option to either use String, StringBuilder,StringBuffer, very useful and you can download it from here.
For Netbeans 6.8 users: http://plugins.netbeans.org/PluginPortal/faces/PluginDetailPage.jsp?pluginid=21008
For Netbeans 6.9 users: http://plugins.netbeans.org/PluginPortal/faces/PluginDetailPage.jsp?pluginid=30004