In an artificial benchmark they are pretty similar, but in real world idiomatic code they are very different to c++. Nearly everything is on the heap so you've got pointers everywhere, dynamic data structures are used everywhere, virtual functions (particularly with java) and interfaces. There's is a reason java was so much slower than native code 20 years ago and that gap has been bridged by CPU progress more then compiler progress.

You are forgetting the crappy programmers as well.

I lost count how many times I have reviewed code where a for loop is used instead of System.arrayCopy().

Or the times I have seen code that my CS data structures teacher would probably give a plain 0, even if done in C.

It's probably for the best those people aren't writing c/c++ ;)

I'd love to make them code in rust, their inability to write code, to even copy/paste it will save so many maintenance problems.

This just isn't true. There's many Java ports of C/C++ applications and benchmarks are usually within 30%.

For the easy tasks. Try a CPU heavy C/C++ app -- like an audio/video editor, number crunching of any kind, etc.

Like I said, the major exception is SIMD instructions. AV and heavy math are a tiny fraction of applications. For these you can use JNI.

There is precedent for this in Netty where they use a native poll mode driver and everything else Java, and it performs about as fast as pure C code on Techempower benchmarks