This has been reported in Vert-x as eclipse-vertx/vert.x#5645 (comment):

• Unsafe's unavailability makes safe init and accessibility checks to perform volatile accesses, which prevent hoisting of array's bound checks
• Unsafe unavailability force PlatformDependent's byte[] multi-bytes accesses to NOT be performed in batch

Both the issues can hit pretty badly newer JDK versions (+24) - we should find a way to leverage VarHandle as much as possible, if available.