diff --git a/Makefile b/Makefile
index e84f9b9..ba9318e 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@
 ARGS:=-n 10 -e 4 -r 3
 
 
-manual-check: manual-check-fortio manual-check-zap
+manual-check: manual-check-fortio manual-check-zap manual-check-slog
 
 manual-check-fortio:
 	$(MAKE) manual-check-param PARAM=fortio
diff --git a/main.go b/main.go
index 40fc2f0..87f1680 100644
--- a/main.go
+++ b/main.go
@@ -3,7 +3,9 @@ package main
 import (
 	"flag"
 	"fmt"
+	"os"
 	"runtime"
+	"runtime/pprof"
 	"sync"
 
 	"fortio.org/cli"
@@ -23,6 +25,8 @@ func main() {
 	numCallsFlag := flag.Int64("n", 100, "Number of calls logged (info level), per goroutine `r`")
 	numExtraFlag := flag.Int("e", 9, "Number of extra debug calls (not logged for each `n` iteration), total call will be n*(e+1)")
 	numGoroutineFlag := flag.Int("r", 10, "Number of go routines to use (multiplies the other numbers)")
+	profileFlag := flag.String("profile", "",
+		"Write a cpu and memory profile to using the given file `prefix` (will add logger name .cpu and .mem)")
 	// Force JSON output even on console and disable expensive debug file/line logging
 	// as well as goroutine id logging which most other loggers don't have.
 	cli.BeforeFlagParseHook = func() {
@@ -39,6 +43,7 @@ func main() {
 	valid := []string{"fortio", "zap", "slog"}
 	cli.CommandBeforeFlags = true
 	cli.CommandHelp = "{" + cli.ColorJoin(log.Colors.Purple, valid...) + "}"
+	log.SetOutput(os.Stdout) // we use stderr for the logger tests, and so stdout for this
 	scli.ServerMain()
 	vSet := sets.FromSlice(valid)
 	if !vSet.Has(cli.Command) {
@@ -47,31 +52,60 @@ func main() {
 	numCalls := *numCallsFlag
 	numExtra := *numExtraFlag
 	numThrds := *numGoroutineFlag
+	profile := ""
+	if *profileFlag != "" {
+		profile = *profileFlag + "-" + cli.Command
+	}
 	log.S(log.Info, "Testing",
 		log.Str("logger", cli.Command),
 		log.Attr("num-calls", numCalls),
 		log.Attr("num-extra", numExtra),
 		log.Attr("num-goroutines", numThrds),
 		log.Attr("gomaxprocs", runtime.GOMAXPROCS(0)),
+		log.Attr("profile", profile),
 	)
 	switch cli.Command {
 	case "fortio":
-		Drive(FortioLog1, numThrds, numCalls, numExtra)
+		Drive(profile, FortioLog1, numThrds, numCalls, numExtra)
 	case "zap":
 		SetupZapLogger()
-		Drive(ZapLog1, numThrds, numCalls, numExtra)
+		Drive(profile, ZapLog1, numThrds, numCalls, numExtra)
 		_ = zlog.Sync()
 	case "slog":
 		SetupSlogLogger()
-		Drive(SlogLog1, numThrds, numCalls, numExtra)
+		Drive(profile, SlogLog1, numThrds, numCalls, numExtra)
 	}
 }
 
+func PrintMemoryStats(start, end *runtime.MemStats) {
+	log.S(log.Info, "Memory stats",
+		log.Attr("alloc", end.Alloc-start.Alloc),
+		log.Attr("total-alloc", end.TotalAlloc-start.TotalAlloc),
+		log.Attr("num-gc", end.NumGC-start.NumGC),
+	)
+}
+
 // Drive the given (iteration logging) function from multiple goroutines.
-func Drive(fn func(string, int64, int), numGoroutines int, numLogged int64, numExtraNotLogged int) {
+func Drive(profile string, fn func(string, int64, int), numGoroutines int, numLogged int64, numExtraNotLogged int) {
 	// wait group
 	wg := sync.WaitGroup{}
 	wg.Add(numGoroutines)
+	var mStart runtime.MemStats
+	var mEnd runtime.MemStats
+	runtime.GC()
+	runtime.ReadMemStats(&mStart)
+	var fc *os.File
+	if profile != "" {
+		var err error
+		fc, err = os.Create(profile + ".cpu")
+		if err != nil {
+			log.Fatalf("Unable to create .cpu profile: %v", err)
+		}
+		if err = pprof.StartCPUProfile(fc); err != nil {
+			log.Critf("Unable to start cpu profile: %v", err)
+		}
+	}
+	log.SetOutput(os.Stderr)
 	for i := 1; i <= numGoroutines; i++ {
 		go func(c int) {
 			fn(fmt.Sprintf("R%d", c), numLogged, numExtraNotLogged)
@@ -79,4 +113,20 @@ func Drive(fn func(string, int64, int), numGoroutines int, numLogged int64, numE
 		}(i)
 	}
 	wg.Wait()
+	runtime.ReadMemStats(&mEnd)
+	log.SetOutput(os.Stdout)
+	if profile != "" {
+		pprof.StopCPUProfile()
+		fm, err := os.Create(profile + ".mem")
+		if err != nil {
+			log.Fatalf("Unable to create .mem profile: %v", err)
+		}
+		runtime.GC() // get up-to-date statistics
+		if err = pprof.WriteHeapProfile(fm); err != nil {
+			log.Critf("Unable to write heap profile: %v", err)
+		}
+		fm.Close()
+		log.S(log.Info, "Wrote profile data", log.Str("cpu", profile+".cpu"), log.Str("mem", profile+".mem"))
+	}
+	PrintMemoryStats(&mStart, &mEnd)
 }
diff --git a/zap.go b/zap.go
index b0383d5..33895c6 100644
--- a/zap.go
+++ b/zap.go
@@ -9,6 +9,8 @@ var zlog *zap.Logger
 
 func SetupZapLogger() {
 	cfg := zap.NewProductionConfig()
+	// Important: turn off sampling!
+	cfg.Sampling = nil
 	if log.GetLogLevel() == log.Debug {
 		cfg.Level.SetLevel(zap.DebugLevel)
 	}