We knew to adjust other JVM settings (e.g. PermGen replaced by Metaspace) but we overlooked that (1) we used a non-default max codecache size and (2) the default for that setting was 3x higher for Java 8.

An unfortunate thing about using non-default JVM settings is that you need to scrutinize them every time you switch Java versions. If I ever go through this again, I will know to pay more attention to every JVM setting we override.