I dunno, I was there in the 2000s and can't remember anyone saying that. I remember a lot of people saying Java's slightly slower execution will not matter that much when processing hardware gets better.
And in particular that garbage collection can be faster than malloc/free.
This is technically true in the case you have a naive C program. There are tons of C programs out there, and some are slow. (But there are more slow Java programs out there)
But it's 100% clear now that GC has a significant cost, and while you can optimize a bad C program, it can be very hard in many cases to optimize the cost of GC away.
C offers more freedom and thus more footguns, but the freedom also means you don't really have a performance cap.
And I prefer GC -- most programs I write will have GC; I just recognize the performance cap, and design accordingly. (In fact I wrote a GC for a subset of C++ for https://oils.pub -- I actually think this is a language with nicer performance properties than Java, mainy due to being AOT)
I will very easily write a faster parallelizable program in Java, before I get the C one even remotely correct and then we haven't even taken into account every future maintenance cost. Also, the way C devs often hide the cost is simply.. less efficient code like copying stuff right and left, etc, which can actually be more "bravely" avoided in managed languages.
The reality is that it's quite the opposite. Java boxed types, lack of control over memory layouts leading to page flapping and false sharing, lack of fast synchronisation primitives, lack of a compiler capable of hinted or automatic loop parallelization lead to Java being totally unsuitable here. The crown goes to FORTRAN in that regard, with C and C++ being second and third places.
Of course theoretically a magic fairy-tale Java compiler could look at the code, recognize all the aforementioned problems and fix them. Of course the language would allow for this to happen totally without changing semantics. But no Java compiler even comes close...
Even better in Rust. You get great memory safety guarantees from the borrow checker helping guide your parallelization, while still being fast and GCless.
It's the best of both worlds.
>Also, the way C devs often hide the cost is simply.. less efficient code like copying stuff right and left, etc, which can actually be more "bravely" avoided in managed languages.
I'd say Rust is again the easiest way to avoid unnecessary copies without sacrificing safety.
For certain other kind of concurrent algorithms, you are in a world of pain and Rust's borrow checker simply refuses to compile a large set of otherwise correct programs.
Especially profile-guided-optimization was hailed as the next big thing, only JIT-ed languages were the ones to be fast, because after some warmup time they would adapt to your data and hardware. Java is still dog-slow...