diff --git a/README.md b/README.md
index 033f82c47..d7a398e75 100644
--- a/README.md
+++ b/README.md
@@ -360,6 +360,8 @@ Fortio `server` has the following feature for the http listening on 8080 (all pa
 | header    | header(s) to add to the reply e.g. `&header=Foo:Bar&header=X:Y` |
 | gzip      | If `Accept-Encoding: gzip` is passed in headers by the caller/client; and `gzip=true` is in the query args, all response will be gzipped; or if `gzip=42.7` is passed, approximately 42.7% will|
 
+`delay`, `close` and `header` query arguments are also supported for the `debug` endpoint which echoes back the request (gzip is always done if `Accept-Encoding: gzip` is present, status is always 200, and the payload is the echo back debug information).
+
 You can set a default value for all these by passing `-echo-server-default-params` to the server command line, for instance:
 `fortio server -echo-server-default-params="delay=0.5s:50,1s:40&status=418"` will make the server respond with http 418 and a delay of either 0.5s half of the time, 1s 40% and no delay in 10% of the calls; unless any `?` query args is passed by the client. Note that the quotes (") are for the shell to escape the ampersand (&) but should not be put in a yaml nor the dynamicflag url for instance.
 
diff --git a/fhttp/http_forwarder.go b/fhttp/http_forwarder.go
index acac34563..e8cb2ee4e 100644
--- a/fhttp/http_forwarder.go
+++ b/fhttp/http_forwarder.go
@@ -247,6 +247,9 @@ func CreateProxyClient() *http.Client {
 			// TODO make configurable, should be fine for now for most but extreme -c values
 			MaxIdleConnsPerHost: 128, // must be more than incoming parallelization; divided by number of fan out if using parallel mode
 			MaxIdleConns:        256,
+			// This avoids Accept-Encoding: gzip being added to outgoing requests when no encoding accept is specified
+			// yet if passed by request, it will do gzip end to end. Issue #624.
+			DisableCompression: true,
 		},
 	}
 	return client
diff --git a/fhttp/http_forwarder_test.go b/fhttp/http_forwarder_test.go
index 19fe034bb..09dbe461d 100644
--- a/fhttp/http_forwarder_test.go
+++ b/fhttp/http_forwarder_test.go
@@ -43,6 +43,10 @@ func TestMultiProxy(t *testing.T) {
 		if !bytes.Contains(data, []byte(payload)) {
 			t.Errorf("Result %s doesn't contain expected payload echo back %q", DebugSummary(data, 1024), payload)
 		}
+		// Issue #624
+		if bytes.Contains(data, []byte("gzip")) {
+			t.Errorf("Result %s contains unexpected gzip (accept encoding)", DebugSummary(data, 1024))
+		}
 		if !bytes.Contains(data, []byte("X-Fortio-Multi-Id: 1")) {
 			t.Errorf("Result %s doesn't contain expected X-Fortio-Multi-Id: 1", DebugSummary(data, 1024))
 		}
diff --git a/fhttp/http_server.go b/fhttp/http_server.go
index bc0264533..219e6bc0b 100644
--- a/fhttp/http_server.go
+++ b/fhttp/http_server.go
@@ -33,6 +33,7 @@ import (
 
 	"fortio.org/fortio/dflag"
 	"fortio.org/fortio/fnet"
+	"fortio.org/fortio/jrpc"
 	"fortio.org/fortio/log"
 	"fortio.org/fortio/version"
 	"golang.org/x/net/http2"
@@ -81,11 +82,7 @@ func EchoHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	log.Debugf("Read %d", len(data))
-	dur := generateDelay(r.FormValue("delay"))
-	if dur > 0 {
-		log.LogVf("Sleeping for %v", dur)
-		time.Sleep(dur)
-	}
+	handleCommonArgs(w, r)
 	statusStr := r.FormValue("status")
 	var status int
 	if statusStr != "" {
@@ -93,34 +90,12 @@ func EchoHandler(w http.ResponseWriter, r *http.Request) {
 	} else {
 		status = http.StatusOK
 	}
-	if log.LogDebug() {
-		// TODO: this easily lead to contention - use 'thread local'
-		rqNum := atomic.AddInt64(&EchoRequests, 1)
-		log.Debugf("Request # %v", rqNum)
-	}
-	if generateClose(r.FormValue("close")) {
-		log.Debugf("Adding Connection:close / will close socket")
-		w.Header().Set("Connection", "close")
-	}
 	gzip := strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") && generateGzip(r.FormValue("gzip"))
 	if gzip {
 		gwz := NewGzipHTTPResponseWriter(w)
 		defer gwz.Close()
 		w = gwz
 	}
-	// process header(s) args, must be before size to compose properly
-	for _, hdr := range r.Form["header"] {
-		log.LogVf("Adding requested header %s", hdr)
-		if len(hdr) == 0 {
-			continue
-		}
-		s := strings.SplitN(hdr, ":", 2)
-		if len(s) != 2 {
-			log.Errf("invalid extra header '%s', expecting Key: Value", hdr)
-			continue
-		}
-		w.Header().Add(s[0], s[1])
-	}
 	size := generateSize(r.FormValue("size"))
 	if size >= 0 {
 		log.LogVf("Writing %d size with %d status", size, status)
@@ -130,7 +105,7 @@ func EchoHandler(w http.ResponseWriter, r *http.Request) {
 	// echo back the Content-Type and Content-Length in the response
 	for _, k := range []string{"Content-Type", "Content-Length"} {
 		if v := r.Header.Get(k); v != "" {
-			w.Header().Set(k, v)
+			jrpc.SetHeaderIfMissing(w.Header(), k, v)
 		}
 	}
 	w.WriteHeader(status)
@@ -139,8 +114,40 @@ func EchoHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// handleCommonArgs common flags for debug and echo handlers.
+// Must be called after body is read.
+func handleCommonArgs(w http.ResponseWriter, r *http.Request) {
+	dur := generateDelay(r.FormValue("delay"))
+	if dur > 0 {
+		log.LogVf("Sleeping for %v", dur)
+		time.Sleep(dur)
+	}
+	if log.LogDebug() {
+		// Note this easily lead to contention, debug mode only (or low qps).
+		rqNum := atomic.AddInt64(&EchoRequests, 1)
+		log.Debugf("Request # %v", rqNum)
+	}
+	if generateClose(r.FormValue("close")) {
+		log.Debugf("Adding Connection:close / will close socket")
+		w.Header().Set("Connection", "close")
+	}
+	// process header(s) args, must be before size to compose properly
+	for _, hdr := range r.Form["header"] {
+		log.LogVf("Adding requested header %s", hdr)
+		if len(hdr) == 0 {
+			continue
+		}
+		s := strings.SplitN(hdr, ":", 2)
+		if len(s) != 2 {
+			log.Errf("invalid extra header '%s', expecting Key: Value", hdr)
+			continue
+		}
+		w.Header().Add(s[0], s[1])
+	}
+}
+
 func writePayload(w http.ResponseWriter, status int, size int) {
-	w.Header().Set("Content-Type", "application/octet-stream")
+	jrpc.SetHeaderIfMissing(w.Header(), "Content-Type", "application/octet-stream")
 	w.Header().Set("Content-Length", strconv.Itoa(size))
 	w.WriteHeader(status)
 	n, err := w.Write(fnet.Payload[:size])
@@ -291,7 +298,7 @@ func DebugHandler(w http.ResponseWriter, r *http.Request) {
 	buf.WriteString("Host: ")
 	buf.WriteString(r.Host)
 
-	var keys []string //nolint:prealloc // header is multi valued map,...
+	keys := make([]string, 0, len(r.Header))
 	for k := range r.Header {
 		keys = append(keys, k)
 	}
@@ -337,7 +344,8 @@ func DebugHandler(w http.ResponseWriter, r *http.Request) {
 			buf.WriteByte('\n')
 		}
 	}
-	w.Header().Set("Content-Type", "text/plain; charset=UTF-8")
+	handleCommonArgs(w, r)
+	jrpc.SetHeaderIfMissing(w.Header(), "Content-Type", "text/plain; charset=UTF-8")
 	if _, err = w.Write(buf.Bytes()); err != nil {
 		log.Errf("Error writing response %v to %v", err, r.RemoteAddr)
 	}
diff --git a/fhttp/http_test.go b/fhttp/http_test.go
index 0dc4c4294..a9d309138 100644
--- a/fhttp/http_test.go
+++ b/fhttp/http_test.go
@@ -1107,34 +1107,46 @@ func TestBadQueryUUIDClient(t *testing.T) {
 	}
 }
 
+// TestDebugHandlerSortedHeaders tests the headers are sorted but
+// also tests post echo back and gzip handling.
 func TestDebugHandlerSortedHeaders(t *testing.T) {
 	m, a := DynamicHTTPServer(false)
-	m.HandleFunc("/debug", DebugHandler)
-	url := fmt.Sprintf("http://localhost:%d/debug", a.Port)
-	o := HTTPOptions{URL: url, DisableFastClient: true}
+	m.Handle("/debug", Gzip(http.HandlerFunc(DebugHandler))) // same as in Serve()
+	// Debug handler does respect the delay arg but not status, status is always 200
+	url := fmt.Sprintf("http://localhost:%d/debug?delay=500ms&status=555", a.Port)
+	// Trigger transparent compression (which will add Accept-Encoding: gzip header)
+	o := HTTPOptions{URL: url, DisableFastClient: true, Compression: true, Payload: []byte("abcd")}
 	o.AddAndValidateExtraHeader("BBB: bbb")
 	o.AddAndValidateExtraHeader("CCC: ccc")
 	o.AddAndValidateExtraHeader("ZZZ: zzz")
 	o.AddAndValidateExtraHeader("AAA: aaa")
 	client, _ := NewClient(&o)
+	now := time.Now()
 	code, data, header := client.Fetch() // used to panic/bug #127
+	duration := time.Since(now)
 	t.Logf("TestDebugHandlerSortedHeaders result code %d, data len %d, headerlen %d", code, len(data), header)
 	if code != http.StatusOK {
 		t.Errorf("Got %d instead of 200", code)
 	}
+	if duration < 500*time.Millisecond {
+		t.Errorf("Got %s instead of 500ms", duration)
+	}
 	// remove the first line ('Φορτίο version...') from the body
 	body := string(data)
 	i := strings.Index(body, "\n")
 	body = body[i+1:]
-	expected := fmt.Sprintf("\nGET /debug HTTP/1.1\n\n"+
+	expected := fmt.Sprintf("\nPOST /debug?delay=500ms&status=555 HTTP/1.1\n\n"+
 		"headers:\n\n"+
 		"Host: localhost:%d\n"+
 		"Aaa: aaa\n"+
+		"Accept-Encoding: gzip\n"+
 		"Bbb: bbb\n"+
 		"Ccc: ccc\n"+
+		"Content-Length: 4\n"+
+		"Content-Type: application/octet-stream\n"+
 		"User-Agent: %s\n"+
 		"Zzz: zzz\n\n"+
-		"body:\n\n\n", a.Port, jrpc.UserAgent)
+		"body:\n\nabcd\n", a.Port, jrpc.UserAgent)
 	if body != expected {
 		t.Errorf("Get body: %s not as expected: %s", body, expected)
 	}
diff --git a/periodic/periodic.go b/periodic/periodic.go
index 73581e9c2..f40245bd8 100644
--- a/periodic/periodic.go
+++ b/periodic/periodic.go
@@ -105,12 +105,13 @@ func (a *Aborter) Abort(wait bool) {
 		return
 	}
 	a.stopRequested = true
-	if a.hasStarted || !wait {
+	started := a.hasStarted
+	if started || !wait {
 		log.LogVf("ABORT Closing %v", a)
 		close(a.StopChan)
 		a.StopChan = nil
 		a.Unlock()
-		if a.hasStarted {
+		if started {
 			log.LogVf("ABORT reading start channel")
 			// shouldn't block/hang, just purging/resetting
 			<-a.StartChan