Wow, thanks a lot for your help. I also thougt about debug infos, but I couldn't find any config information to exclude debug infos from the binary. But with your hint it works! With the "strip command" the size of the test app reduces from 12 MB to 1.6 MB.
Only, opposite of the FAQ (<quote>"You can use a program called "strip" to remove the debug symbols from the executable file. It is located under lazarus dir lazarus\pp\bin\i386-win32\. </quote>)
in my case the "strip.exe" was located under lazarus\fpc\2.2.4\bin\i386-win32\. But at last - the problem is solved. So the Lazarus community got a new fan now using this great development sytem from now on.
Ray