Few things to benchmark

httpd_sample.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"
)

var (
	test_string = "This is just a test string."
)

func format_string(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, test_string)
}

func faux_cache() func(http.ResponseWriter, *http.Request) {
	reader := strings.NewReader(test_string)

	return func(w http.ResponseWriter, r *http.Request) {
		io.Copy(w, reader)
	}
}

func from_disk() func(http.ResponseWriter, *http.Request) {
	fh, err := os.Create("temp_test_file")
	if err != nil {
		panic(err)
	}
	defer fh.Close()

	fmt.Fprintf(fh, test_string)

	return func(w http.ResponseWriter, r *http.Request) {
		fh, err := os.Open("temp_test_file")
		if err != nil {
			panic(err)
		}
		defer fh.Close()
		io.Copy(w, fh)
	}
}

func main() {
	http.HandleFunc("/1", format_string)
	http.HandleFunc("/2", faux_cache())
	http.HandleFunc("/3", from_disk())
	http.ListenAndServe(":8080", nil)
}