Umm... here
https://blog.twitch.tv/gos-march-to-low-latency-gc-a6fa96f06...
It sort of looks like language developers are finally getting the point that while you can easily deal with a throughput problem by just throwing faster processors, more processors, and or memory at at it, working around long gc pauses is just pain all around.
The JVM is in HFT in because of sheer inertia; it has been worked on for so many years to shoehorn it in, and some smart people have made it work. The tooling is mature, and there are alternative syntaxes close to it like Kotlin that remove a lot of the noise for code review and maintenance.
The JVM is the reason I stayed away from Clojure, even though I like Lisp/Scheme syntax and the semantics. Where is Clojure-clr nowadays?
There's also talk about the possible removal of sun.misc.Unsafe in Java 9¹.
¹ http://blog.dripstat.com/removal-of-sun-misc-unsafe-a-disast...
The Oracle people are right about this one. Rip it out and sterilize the wound with fire.
That said the amount of restrictions you have makes it really painful(needing to use pre-allocated wrappers if you want to read more than intrinsic types, not being able to grow/shrink anything). There's sun.misc.Unsafe, but that isn't available on every JVM implementation.
A GC is going to by nature introduce pauses if since at some point it's going to need to do work on the memory you hold. There's a set of tunable tradeoffs but it will impact latency.
I guess my meta point is if throughput and latency are paramount to you then you should really consider a language suited for it. For me today that would be Rust or C++ depending on how risk-adverse the organization you're working with is.
[1] https://google.github.io/flatbuffers/