You can get within 20% the performance for 1/10th the cost by using a modern fast language (rust, d, nim, go), and within 50% for even cheaper by using c# or java.
Of my short encounter with "modern" webdev, I found that running out of RAM was far faster than running out of CPU, even with every trick possible thrown to increase GC aggressiveness.
RAM is by far more discriminately priced on all these new "cloud" hostings, and has the most unpredictable performance change with size. Even on real hardware, going for high RAM servers is quite expensive.
While CPU, or I/O saturation naturally throttles itself, RAM exhaustion is rarely pretty, and hard to proof your software against. Most disconcerting about this is that your RUST, GO, or the TRUE ENTERPRISE JAVA®, don't really use that RAM at all. Most of "modern languages" RAM content is just zeroes, and empty buffers.
Also as shown by TechEmpower benchmark, in "webdev" field, C/C++ doesn't have proper/official driver to Postgres with pipelined support, thus even lose to Java in the fortunes benchmark.
Nowadays, they are using a fork of libpq with batch API that has not been merged for 6 years in order to compete.
So, lacking of good library support in "webdev" field will put C/C++ at extreme disadvantages compare to other "webdev"-friendly languages.
> The system [LMAX] is built on the JVM platform and centers on a Business Logic Processor that can handle 6 million orders per second on a single thread. The Business Logic Processor runs entirely in-memory using event sourcing.
Your GP didn't just mention Rust, they also mentioned C# and Java, so when your parent refers to GC the more charitable interpretation is that they were using C# or Java and responding to that part of the message.
