I know that Java resisted improving their FFI for years because they preferred that the JIT get the extra resources. And that customers not bail out of Java every time they couldn’t figure out how to make it faster. There’s a case I recall from when HotSpot was still young, where the Java GUI team moved part of the graphics pipeline to the FFI in one release, hotspot got faster in the next, and then they rolled back the changes because it was now faster without the FFI.

But eventually your compiler is good enough that the FFI Is now your bottleneck, and you need to do something.