How do you evaluate whether a Julia system is scaling efficiently?

Scaling efficiency is measured by speedup, allocation growth, dispatch overhead, and communication cost across workers.

A Julia system scales efficiently when adding compute resources results in near-linear performance improvement. Bottlenecks often arise from communication overhead in distributed systems, GC pressure in memory-heavy workloads, or type instability preventing optimization. Profiling must include both single-node and multi-node behavior.