Book: The Complete Guide to Go Programming Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub A team I talked to last month was chasing a CPU spike on a hot-path service. Twelve thousand requests per second, p99 crawling north of forty milliseconds for no obvious reason. The code looked clean: a request counter behind a channel, a goroutine that drained the channel and updated a metric. "Share memory by communicating," the slogan goes. They followed it. The fix was three lines. They replaced the counter channel with a sync.Mutex and a plain int64 . CPU dropped by roughly a third. p99 came back to a flat line. The channel was the bottleneck. This is not a story about channels being bad. Channels are the right tool for the job they were designed for.…