If your #JDeveloper 12.2.1 is slow have a look at the solution that worked for this customer - there is a patch you might want to apply to your environment (and disabling the TopLink extension is another thing to consider).
@JDeveloper Support extension is ok, but we need a new version of #JDeveloper and #OracleADF to migrate to Java 11 (We are waiting years for 14.1.2 version), @Oracle and @ShayOracle please help us with this