diff --git a/.github/README.md b/.github/README.md
index 2aa8fba..8df418a 100644
--- a/.github/README.md
+++ b/.github/README.md
@@ -116,6 +116,10 @@ func controller(context *fiber.Ctx) error {
 
 Full Fiber example is available at https://github.com/peterdee/filtering-backend
 
+### Performance
+
+Brille uses `sync.WaitGroup` for performance optimization starting with version **v2.0.4**. Image processing can be done in several threads (by default Brille uses `runtime.NumCPU()` value). 
+
 ### Available filters
 
 - **Binary**: converts an image to 1-bit black and white. Requires a threshold value (`uint8`, 0 to 255):
diff --git a/filters/emboss.go b/filters/emboss.go
index 29ae9d6..a55f6b7 100644
--- a/filters/emboss.go
+++ b/filters/emboss.go
@@ -25,11 +25,11 @@ func Emboss(file io.Reader) (io.Reader, string, error) {
 	if convertationError != nil {
 		return nil, "", convertationError
 	}
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	pixLen := len(img.Pix)
-	result := make([]uint8, pixLen)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
+	result := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
 	processing := func(thread int) {
 		defer wg.Done()
diff --git a/filters/gaussian-blur.go b/filters/gaussian-blur.go
index 5d4335c..a8f9544 100644
--- a/filters/gaussian-blur.go
+++ b/filters/gaussian-blur.go
@@ -41,12 +41,11 @@ func GaussianBlur(file io.Reader, sigma float64) (io.Reader, string, error) {
 	sigma = utilities.Clamp(sigma, 99, 0)
 	kernel := createKernel(sigma)
 	pixLen := len(img.Pix)
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
-	temp := make([]uint8, pixLen)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
+	temp := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
-
 	processing := func(start int, direction string) {
 		defer wg.Done()
 		end := utilities.ClampMax(start+pixPerThread, pixLen)
@@ -88,20 +87,15 @@ func GaussianBlur(file io.Reader, sigma float64) (io.Reader, string, error) {
 			}
 		}
 	}
-
-	// horizontal
 	for t := 0; t < threads; t += 1 {
 		wg.Add(1)
 		go processing(pixPerThread*t, "horizontal")
 	}
 	wg.Wait()
-
-	// vertical
 	for t := 0; t < threads; t += 1 {
 		wg.Add(1)
 		go processing(pixPerThread*t, "vertical")
 	}
 	wg.Wait()
-
 	return utilities.EncodeResult(img, format)
 }
diff --git a/filters/kuwahara.go b/filters/kuwahara.go
index 0aa0026..b6725ff 100644
--- a/filters/kuwahara.go
+++ b/filters/kuwahara.go
@@ -12,12 +12,12 @@ func Kuwahara(file io.Reader, radius uint) (io.Reader, string, error) {
 	if convertationError != nil {
 		return nil, "", convertationError
 	}
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	radiusInt := int(radius)
 	pixLen := len(img.Pix)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
 	result := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
 	processing := func(thread int) {
 		defer wg.Done()
diff --git a/filters/laplacian.go b/filters/laplacian.go
index a29f8be..ab43563 100644
--- a/filters/laplacian.go
+++ b/filters/laplacian.go
@@ -18,11 +18,11 @@ func Laplacian(file io.Reader) (io.Reader, string, error) {
 	if convertationError != nil {
 		return nil, "", convertationError
 	}
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	pixLen := len(img.Pix)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
 	result := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
 	processing := func(thread int) {
 		defer wg.Done()
diff --git a/filters/sharpen.go b/filters/sharpen.go
index 9871f48..ffdf655 100644
--- a/filters/sharpen.go
+++ b/filters/sharpen.go
@@ -22,8 +22,8 @@ func Sharpen(file io.Reader, amount uint) (io.Reader, string, error) {
 	pixLen := len(img.Pix)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	result := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
 	processing := func(thread int) {
 		defer wg.Done()
diff --git a/filters/sobel.go b/filters/sobel.go
index 4d9968f..123a659 100644
--- a/filters/sobel.go
+++ b/filters/sobel.go
@@ -28,8 +28,8 @@ func Sobel(file io.Reader) (io.Reader, string, error) {
 	pixLen := len(img.Pix)
 	threads := utilities.GetThreads()
 	pixPerThread := utilities.GetPixPerThread(pixLen, threads)
-	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	result := make([]uint8, pixLen)
+	width, height := img.Rect.Max.X, img.Rect.Max.Y
 	var wg sync.WaitGroup
 	processing := func(thread int) {
 		defer wg.Done()