diff --git a/bar.go b/bar.go
index 043163d..1a4c66f 100644
--- a/bar.go
+++ b/bar.go
@@ -5,7 +5,6 @@
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"strings"
 	"time"
@@ -34,16 +33,15 @@
 	priority int // used by heap
 	index    int // used by heap
 
-	extendedLines        int
-	toShutdown           bool
-	toDrop               bool
-	noPop                bool
-	hasAverageDecorators bool
-	hasEwmaDecorators    bool
-	operateState         chan func(*bState)
-	frameCh              chan io.Reader
-	syncTableCh          chan [][]chan int
-	completed            chan bool
+	extendedLines     int
+	toShutdown        bool
+	toDrop            bool
+	noPop             bool
+	hasEwmaDecorators bool
+	operateState      chan func(*bState)
+	frameCh           chan io.Reader
+	syncTableCh       chan [][]chan int
+	completed         chan bool
 
 	// cancel is called either by user or on complete event
 	cancel func()
@@ -113,19 +111,12 @@
 }
 
 // ProxyReader wraps r with metrics required for progress tracking.
+// Panics if r is nil.
 func (b *Bar) ProxyReader(r io.Reader) io.ReadCloser {
 	if r == nil {
-		return nil
-	}
-	rc, ok := r.(io.ReadCloser)
-	if !ok {
-		rc = ioutil.NopCloser(r)
-	}
-	prox := &proxyReader{rc, b, time.Now()}
-	if wt, ok := r.(io.WriterTo); ok {
-		return &proxyWriterTo{prox, wt}
-	}
-	return prox
+		panic("expected non nil io.Reader")
+	}
+	return newProxyReader(r, b)
 }
 
 // ID returs id of the bar.
@@ -248,9 +239,6 @@
 // iteration's duration. Panics if called before *Bar.Incr... family
 // methods.
 func (b *Bar) DecoratorEwmaUpdate(dur time.Duration) {
-	if !b.hasEwmaDecorators {
-		return
-	}
 	select {
 	case b.operateState <- func(s *bState) {
 		ewmaIterationUpdate(false, s, dur)
@@ -264,9 +252,6 @@
 // if you need to adjust start time of all average based decorators
 // or after progress resume.
 func (b *Bar) DecoratorAverageAdjust(start time.Time) {
-	if !b.hasAverageDecorators {
-		return
-	}
 	select {
 	case b.operateState <- func(s *bState) {
 		for _, d := range s.averageDecorators {
@@ -389,7 +374,6 @@
 		s.ewmaDecorators = ewmaDecorators
 		s.shutdownListeners = shutdownListeners
 	}
-	b.hasAverageDecorators = len(averageDecorators) != 0
 	b.hasEwmaDecorators = len(ewmaDecorators) != 0
 }
 
diff --git a/proxyreader.go b/proxyreader.go
index 8323986..0efb09a 100644
--- a/proxyreader.go
+++ b/proxyreader.go
@@ -2,42 +2,90 @@
 
 import (
 	"io"
+	"io/ioutil"
 	"time"
 )
 
 type proxyReader struct {
 	io.ReadCloser
 	bar *Bar
-	iT  time.Time
 }
 
-func (prox *proxyReader) Read(p []byte) (int, error) {
-	n, err := prox.ReadCloser.Read(p)
-	if n > 0 {
-		prox.bar.IncrBy(n)
-		prox.bar.DecoratorEwmaUpdate(time.Since(prox.iT))
-		prox.iT = time.Now()
-	}
+func (x *proxyReader) Read(p []byte) (int, error) {
+	n, err := x.ReadCloser.Read(p)
+	x.bar.IncrBy(n)
 	if err == io.EOF {
-		go prox.bar.SetTotal(0, true)
+		go x.bar.SetTotal(0, true)
 	}
 	return n, err
 }
 
 type proxyWriterTo struct {
-	*proxyReader
-	wt io.WriterTo
+	io.ReadCloser // *proxyReader
+	wt            io.WriterTo
+	bar           *Bar
 }
 
-func (prox *proxyWriterTo) WriteTo(w io.Writer) (int64, error) {
-	n, err := prox.wt.WriteTo(w)
-	if n > 0 {
-		prox.bar.IncrInt64(n)
-		prox.bar.DecoratorEwmaUpdate(time.Since(prox.iT))
-		prox.iT = time.Now()
-	}
+func (x *proxyWriterTo) WriteTo(w io.Writer) (int64, error) {
+	n, err := x.wt.WriteTo(w)
+	x.bar.IncrInt64(n)
 	if err == io.EOF {
-		go prox.bar.SetTotal(0, true)
+		go x.bar.SetTotal(0, true)
 	}
 	return n, err
 }
+
+type ewmaProxyReader struct {
+	io.ReadCloser // *proxyReader
+	bar           *Bar
+	iT            time.Time
+}
+
+func (x *ewmaProxyReader) Read(p []byte) (int, error) {
+	n, err := x.ReadCloser.Read(p)
+	if n > 0 {
+		x.bar.DecoratorEwmaUpdate(time.Since(x.iT))
+		x.iT = time.Now()
+	}
+	return n, err
+}
+
+type ewmaProxyWriterTo struct {
+	io.ReadCloser             // *ewmaProxyReader
+	wt            io.WriterTo // *proxyWriterTo
+	bar           *Bar
+	iT            time.Time
+}
+
+func (x *ewmaProxyWriterTo) WriteTo(w io.Writer) (int64, error) {
+	n, err := x.wt.WriteTo(w)
+	if n > 0 {
+		x.bar.DecoratorEwmaUpdate(time.Since(x.iT))
+		x.iT = time.Now()
+	}
+	return n, err
+}
+
+func newProxyReader(r io.Reader, bar *Bar) io.ReadCloser {
+	wt, isWriterTo := r.(io.WriterTo)
+	rc := toReadCloser(r)
+	rc = &proxyReader{rc, bar}
+
+	if bar.hasEwmaDecorators {
+		now := time.Now()
+		rc = &ewmaProxyReader{rc, bar, now}
+		if isWriterTo {
+			rc = &ewmaProxyWriterTo{rc, wt, bar, now}
+		}
+	} else if isWriterTo {
+		rc = &proxyWriterTo{rc, wt, bar}
+	}
+	return rc
+}
+
+func toReadCloser(r io.Reader) io.ReadCloser {
+	if rc, ok := r.(io.ReadCloser); ok {
+		return rc
+	}
+	return ioutil.NopCloser(r)
+}