Playing with m2e 1.6 on my new MBP, I imported the wildfly projects in my workspace, then deleted everything.
Before import heap was at ~80MB, after th 135 projects and forcing GC, it doesn't go down 280MB. I then took a heap dump (https://www.dropbox.com/s/gmxy6ofdwrtb8g2/java_pid14384.0002.hprof.zip), loaded it into Eclipse Memory Analyzer and looked for org.jboss.* components.

It seems we retain many XModelMetadataIpl, JSF2Project, KbProject instances and a bunch of other JBT classes, that should be cleaned up when projects are deleted from workspace