Hi,
I have some new results:
some of the slowness comes from hiearchical project structure as suspected. With parent-projects (= maven projects with <packaging>pom</packaging> in workspace) "sees" Eclipse the project 2x or more:
\parentProject\suproject1\target\Klass1.class
\parentProject\suproject2\target\Klass2.class
\suproject1\target\Klass1.class
\suproject2\target\Klass2.class
...
and NoDataDeltaNode are created many times (for all *.class for example : 1)\parentProject\suproject1\target\Klass1.class 2)\suproject1\target\Klass1.class : but this is the same class)
As a quick workaround I deleted all non-java project from workspace (as result are in the workspace only end-projects = leafs in the maven-tree-project structure, no resource exists 2x in eclipse now. After this change : only 20 min to build, ie 33% improvement.
In this case was the quick workaround the deletion of parent projects. Another solution is maven with flat layout. Any others solutions / ideas ?
I have more result, but I'll write them as a separate mail-thread.