Running the SunOne Appserver 8.0 with JDK 1.4.2 build 22 and these arguments:
-server -XX:+PrintCompilation
we obeserved that classes that were killed because of concurrent class loading were never recompiled.

Depending on the particular classes that never get recompiled, this could be a significant performance penalty. In the attached print compilation output, some of the non-compiled methods include HashMap.hash and decodeArrayLoop in the NIO decoders.