I am aware that you can hit really good latency targets with GC'ed languages, like in the video game and finance industry. Whenever I investigate examples, though, I find the devs have to go through a ton of effort to avoid memory allocations, and then I ask if using the GC'ed language was even worth it in the first place?

I'm actually fascinated with the idea of going off-heap in the hotspots of GC'ed languages to get better performance. Netty, for instance, relies on off-heap allocations to achieve better networking performance. But, once you do so, you start incurring the disadvantages of languages like C/C++, and it can get complicated mixing the two styles of code.