It is written in go and compiled. Go is responsible for high parallelism. The fact it is compiled is an advantage over javascript-based bundlers because they are re-compiled every time you start building the source code (did I get that right?).

partially. we should not overstate the impact of Go. if you read his design principles doc, he also prioritized parallelization and minimizing JS AST passes. those are surely at least as important as language choice.