Why not just pass -Xcomp? From the docs[1]: "You can completely disable interpretation of Java methods before compilation by specifying the -Xcomp option."
[1] https://docs.oracle.com/javase/8/docs/technotes/tools/window...
[1] https://docs.oracle.com/javase/8/docs/technotes/tools/window...
If you're benchmarking java code and the method was not called enough times before you measure, you're measuring code compiled by C1 (or even interpreted).
The performance gap between Java and C is on the order of x2 to x5.