Greetings,
By default the Java heap memory size in Kinetis Design Studio V3.0.0 (and earlier version) is set to 512 MBytes.
Depending on Eclipse usage (number of open projects, views open) that might not be enough, causing Eclipse to react slowly.
The solution is to increase the available memory for Java.
The attached technical note describes the problem and how to increase the heap size.
Erich