Lack of value types means greater allocation by default - so it needs escape analysis to avoid it.
Type erasure for generic types means speculative optimisation and deoptimisation steps for types.
etc
Doesn't mean the .NET Jit can't improve in these areas (e.g. now its doing devirtualization for .NET Core 2.1, and escape analysis would be great) - but it does start in a better place.
Empirically, I've found that value types generally only offer a tangible perf benefit when they're the size of a pointer or smaller. There aren't a whole lot of spots where that comes into play. Primitives, sure, but Java also has those. Beyond that, maybe you'd see some difference in code that does a lot of date calculations, maybe. I've done some slightly obscene and shameful optimizations around packing data into 64-bit structures in the past, but those are pretty special cases.
Well, seems that the JVM designers disagree, there's been a lot of work put into fixing this, see 'Project Valhalla' for instance
https://www.infoq.com/news/2016/11/valhalla-Implementation-p... http://www.jesperdj.com/2015/10/04/project-valhalla-value-ty...
Oracle is not a company that gives money away for free.
Fintech is one of the areas that is slowly moving from C++ into Java and doesn't do it faster because they cannot move all the kind of code they have into Java, hence Oracle efforts.
Or why we are starting to see languages like Pony and Chapel pop up.
Are you referring to various trading and middle ware engines? Or mostly FE projects ?
http://www.minecraftforum.net/forums/mapping-and-modding-jav...
(Allegedly, a Minecraft update added significant strain on the garbage collector by switching the codebase from using separate variables/parameters for x, y, and z coordinates to using a single “BlockPos” object.)
The spot where you take a hit is when you've got a scattering of individual objects that are being passed into and out of functions. There, the extra data copying has a tendency to outweigh the other benefits. And that's a more likely scenario for most kind of the kinds of business apps that .NET and Java are typically used for.