That "all" makes for a bold claim.
"well I need to go faster than Node..."
.NET is generally faster than Node.js, at least based on most benchmarks I've seen.
" so do I need to go to C?"
Is there any other official/stable extension mechanism for Node?
"Java is slow too."
That one, I agree, is false. Java is at least as fast as .NET.
"But the C library ecosystem is _rough_...."
The C library ecosystem is very rough. The lack of memory management and the overall creakiness of C showing its age are easily apparent.
They would be utterly mistaken on all accounts.