diff --git a/benchmark_test.go b/benchmark_test.go
new file mode 100644
index 00000000..7abd697b
--- /dev/null
+++ b/benchmark_test.go
@@ -0,0 +1,52 @@
+package yaml_test
+
+import (
+	"testing"
+
+	"github.com/goccy/go-yaml"
+	goyaml2 "gopkg.in/yaml.v2"
+	goyaml3 "gopkg.in/yaml.v3"
+)
+
+func Benchmark(b *testing.B) {
+	const src = `---
+id: 1
+message: Hello, World
+verified: true
+elements:
+  - one
+  - 0.02
+  - null
+  - -inf
+`
+	type T struct {
+		ID       int    `yaml:"id"`
+		Message  string `yaml:"message"`
+		Verified bool   `yaml:"verified,omitempty"`
+	}
+
+	b.Run("gopkg.in/yaml.v2", func(b *testing.B) {
+		var t T
+		for i := 0; i < b.N; i++ {
+			if err := goyaml2.Unmarshal([]byte(src), &t); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+	b.Run("gopkg.in/yaml.v3", func(b *testing.B) {
+		var t T
+		for i := 0; i < b.N; i++ {
+			if err := goyaml3.Unmarshal([]byte(src), &t); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+	b.Run("github.com/goccy/go-yaml", func(b *testing.B) {
+		var t T
+		for i := 0; i < b.N; i++ {
+			if err := yaml.Unmarshal([]byte(src), &t); err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+}
diff --git a/decode.go b/decode.go
index 9bd0dddf..e1c1f6d8 100644
--- a/decode.go
+++ b/decode.go
@@ -1,6 +1,7 @@
 package yaml
 
 import (
+	"bytes"
 	"encoding/base64"
 	"fmt"
 	"io"
@@ -82,6 +83,22 @@ func (d *Decoder) castToFloat(v interface{}) interface{} {
 	return 0
 }
 
+func (d *Decoder) setToMapValue(node ast.Node, m map[string]interface{}) {
+	switch n := node.(type) {
+	case *ast.MappingValueNode:
+		if n.Key.Type() == ast.MergeKeyType {
+			d.setToMapValue(n.Value, m)
+		} else {
+			key := n.Key.GetToken().Value
+			m[key] = d.nodeToValue(n.Value)
+		}
+	case *ast.MappingNode:
+		for _, value := range n.Values {
+			d.setToMapValue(value, m)
+		}
+	}
+}
+
 func (d *Decoder) nodeToValue(node ast.Node) interface{} {
 	switch n := node.(type) {
 	case *ast.NullNode:
@@ -122,28 +139,23 @@ func (d *Decoder) nodeToValue(node ast.Node) interface{} {
 	case *ast.LiteralNode:
 		return n.Value.GetValue()
 	case *ast.MappingValueNode:
-		m := map[string]interface{}{}
 		if n.Key.Type() == ast.MergeKeyType {
-			mapValue := d.nodeToValue(n.Value).(map[string]interface{})
-			for k, v := range mapValue {
-				m[k] = v
-			}
-		} else {
-			key := n.Key.GetToken().Value
-			m[key] = d.nodeToValue(n.Value)
+			m := map[string]interface{}{}
+			d.setToMapValue(n.Value, m)
+			return m
+		}
+		key := n.Key.GetToken().Value
+		return map[string]interface{}{
+			key: d.nodeToValue(n.Value),
 		}
-		return m
 	case *ast.MappingNode:
-		m := map[string]interface{}{}
+		m := make(map[string]interface{}, len(n.Values))
 		for _, value := range n.Values {
-			subMap := d.nodeToValue(value).(map[string]interface{})
-			for k, v := range subMap {
-				m[k] = v
-			}
+			d.setToMapValue(value, m)
 		}
 		return m
 	case *ast.SequenceNode:
-		v := []interface{}{}
+		v := make([]interface{}, 0, len(n.Values))
 		for _, value := range n.Values {
 			v = append(v, d.nodeToValue(value))
 		}
@@ -946,11 +958,11 @@ func (d *Decoder) Decode(v interface{}) error {
 	if rv.Type().Kind() != reflect.Ptr {
 		return errors.ErrDecodeRequiredPointerType
 	}
-	bytes, err := ioutil.ReadAll(d.reader)
-	if err != nil {
-		return errors.Wrapf(err, "failed to read buffer")
+	var buf bytes.Buffer
+	if _, err := io.Copy(&buf, d.reader); err != nil {
+		return errors.Wrapf(err, "failed to copy from reader")
 	}
-	node, err := d.decode(bytes)
+	node, err := d.decode(buf.Bytes())
 	if err != nil {
 		return errors.Wrapf(err, "failed to decode")
 	}
diff --git a/scanner/context.go b/scanner/context.go
index 0f500fa3..a6f4ec1c 100644
--- a/scanner/context.go
+++ b/scanner/context.go
@@ -1,41 +1,68 @@
 package scanner
 
 import (
-	"strings"
+	"sync"
 
 	"github.com/goccy/go-yaml/token"
 )
 
 // Context context at scanning
 type Context struct {
-	idx          int
-	size         int
-	src          []rune
-	buf          []rune
-	obuf         []rune
-	tokens       token.Tokens
-	isRawFolded  bool
-	isLiteral    bool
-	isFolded     bool
-	isSingleLine bool
-	literalOpt   string
-}
+	idx                int
+	size               int
+	notSpaceCharPos    int
+	notSpaceOrgCharPos int
+	src                []rune
+	buf                []rune
+	obuf               []rune
+	tokens             token.Tokens
+	isRawFolded        bool
+	isLiteral          bool
+	isFolded           bool
+	isSingleLine       bool
+	literalOpt         string
+}
+
+var (
+	ctxPool = sync.Pool{
+		New: func() interface{} {
+			return createContext()
+		},
+	}
+)
 
-func newContext(src []rune) *Context {
+func createContext() *Context {
 	return &Context{
 		idx:          0,
-		size:         len(src),
-		src:          src,
 		tokens:       token.Tokens{},
-		buf:          make([]rune, 0, len(src)),
-		obuf:         make([]rune, 0, len(src)),
 		isSingleLine: true,
 	}
 }
 
+func newContext(src []rune) *Context {
+	ctx := ctxPool.Get().(*Context)
+	ctx.reset(src)
+	return ctx
+}
+
+func (c *Context) release() {
+	ctxPool.Put(c)
+}
+
+func (c *Context) reset(src []rune) {
+	c.idx = 0
+	c.size = len(src)
+	c.src = src
+	c.tokens = c.tokens[:0]
+	c.resetBuffer()
+	c.isSingleLine = true
+}
+
 func (c *Context) resetBuffer() {
 	c.buf = c.buf[:0]
 	c.obuf = c.obuf[:0]
+	c.notSpaceCharPos = 0
+	c.notSpaceOrgCharPos = 0
 }
 
 func (c *Context) isSaveIndentMode() bool {
@@ -57,20 +84,29 @@ func (c *Context) addToken(tk *token.Token) {
 }
 
 func (c *Context) addBuf(r rune) {
+	if len(c.buf) == 0 && r == ' ' {
+		return
+	}
 	c.buf = append(c.buf, r)
+	if r != ' ' {
+		c.notSpaceCharPos = len(c.buf)
+	}
 }
 
 func (c *Context) addOriginBuf(r rune) {
 	c.obuf = append(c.obuf, r)
+	if r != ' ' {
+		c.notSpaceOrgCharPos = len(c.obuf)
+	}
 }
 
 func (c *Context) removeRightSpaceFromBuf() int {
-	trimmedBuf := strings.TrimRight(string(c.obuf), " ")
-	buflen := len([]rune(trimmedBuf))
+	trimmedBuf := c.obuf[:c.notSpaceOrgCharPos]
+	buflen := len(trimmedBuf)
 	diff := len(c.obuf) - buflen
 	if diff > 0 {
 		c.obuf = c.obuf[:buflen]
-		c.buf = []rune(c.bufferedSrc())
+		c.buf = c.bufferedSrc()
 	}
 	return diff
 }
@@ -133,9 +169,12 @@ func (c *Context) nextPos() int {
 	return c.idx + 1
 }
 
-func (c *Context) bufferedSrc() string {
-	src := strings.TrimLeft(string(c.buf), " ")
-	src = strings.TrimRight(src, " ")
+func (c *Context) existsBuffer() bool {
+	return len(c.bufferedSrc()) != 0
+}
+
+func (c *Context) bufferedSrc() []rune {
+	src := c.buf[:c.notSpaceCharPos]
 	if len(src) > 0 && src[len(src)-1] == '\n' && c.isDocument() && c.literalOpt == "-" {
 		// remove end '\n' character
 		src = src[:len(src)-1]
@@ -151,8 +190,7 @@ func (c *Context) bufferedToken(pos *token.Position) *token.Token {
 	if len(source) == 0 {
 		return nil
 	}
-	tk := token.New(source, string(c.obuf), pos)
-	c.buf = c.buf[:0]
-	c.obuf = c.obuf[:0]
+	tk := token.New(string(source), string(c.obuf), pos)
+	c.resetBuffer()
 	return tk
 }
diff --git a/scanner/scanner.go b/scanner/scanner.go
index b8b6a276..26228473 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -61,8 +61,7 @@ func (s *Scanner) bufferedToken(ctx *Context) *token.Token {
 		s.savedPos = nil
 		return tk
 	}
-	trimmedSrc := strings.TrimLeft(string(ctx.buf), " ")
-	size := len([]rune(trimmedSrc))
+	size := len(ctx.buf)
 	return ctx.bufferedToken(&token.Position{
 		Line:        s.line,
 		Column:      s.column - size,
@@ -95,7 +94,7 @@ func (s *Scanner) isNeededKeepPreviousIndentNum(ctx *Context, c rune) bool {
 	if ctx.isDocument() {
 		return true
 	}
-	if c == '-' && ctx.bufferedSrc() != "" {
+	if c == '-' && ctx.existsBuffer() {
 		return true
 	}
 	return false
@@ -262,7 +261,7 @@ func (s *Scanner) scanLiteral(ctx *Context, c rune) {
 	if ctx.isEOS() {
 		ctx.addBuf(c)
 		value := ctx.bufferedSrc()
-		ctx.addToken(token.New(value, string(ctx.obuf), s.pos()))
+		ctx.addToken(token.New(string(value), string(ctx.obuf), s.pos()))
 		ctx.resetBuffer()
 		s.progressColumn(ctx, 1)
 	} else if s.isNewLineChar(c) {
@@ -322,7 +321,7 @@ func (s *Scanner) scanLiteralHeader(ctx *Context) (pos int, err error) {
 func (s *Scanner) scanNewLine(ctx *Context, c rune) {
 	if len(ctx.buf) > 0 && s.savedPos == nil {
 		s.savedPos = s.pos()
-		s.savedPos.Column -= len([]rune(ctx.bufferedSrc()))
+		s.savedPos.Column -= len(ctx.bufferedSrc())
 	}
 
 	// if the following case, origin buffer has unnecessary two spaces.
@@ -334,7 +333,9 @@ func (s *Scanner) scanNewLine(ctx *Context, c rune) {
 	if removedNum > 0 {
 		s.column -= removedNum
 		s.offset -= removedNum
-		s.savedPos.Column -= removedNum
+		if s.savedPos != nil {
+			s.savedPos.Column -= removedNum
+		}
 	}
 
 	if ctx.isEOS() {
@@ -373,7 +374,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 		}
 		switch c {
 		case '{':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.MappingStart(string(ctx.obuf), s.pos()))
 				s.startedFlowMapNum++
@@ -381,7 +382,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '}':
-			if ctx.bufferedSrc() == "" || s.startedFlowMapNum > 0 {
+			if !ctx.existsBuffer() || s.startedFlowMapNum > 0 {
 				ctx.addToken(s.bufferedToken(ctx))
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.MappingEnd(string(ctx.obuf), s.pos()))
@@ -412,7 +413,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				pos += 2
 				return
 			}
-			if ctx.bufferedSrc() != "" && s.isChangedToIndentStateUp() {
+			if ctx.existsBuffer() && s.isChangedToIndentStateUp() {
 				// raw folded
 				ctx.isRawFolded = true
 				ctx.addBuf(c)
@@ -420,7 +421,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				s.progressColumn(ctx, 1)
 				continue
 			}
-			if ctx.bufferedSrc() != "" && ctx.isSingleLine {
+			if ctx.existsBuffer() && ctx.isSingleLine {
 				// '-' is literal
 				ctx.addBuf(c)
 				ctx.addOriginBuf(c)
@@ -438,7 +439,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '[':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.SequenceStart(string(ctx.obuf), s.pos()))
 				s.startedFlowSequenceNum++
@@ -446,7 +447,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case ']':
-			if ctx.bufferedSrc() == "" || s.startedFlowSequenceNum > 0 {
+			if !ctx.existsBuffer() || s.startedFlowSequenceNum > 0 {
 				s.addBufferedTokenIfExists(ctx)
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.SequenceEnd(string(ctx.obuf), s.pos()))
@@ -476,7 +477,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '|', '>':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				progress, err := s.scanLiteralHeader(ctx)
 				if err != nil {
 					// TODO: returns syntax error object
@@ -487,7 +488,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				continue
 			}
 		case '!':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				token, progress := s.scanTag(ctx)
 				ctx.addToken(token)
 				s.progressColumn(ctx, progress)
@@ -498,20 +499,20 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '%':
-			if ctx.bufferedSrc() == "" && s.indentNum == 0 {
+			if !ctx.existsBuffer() && s.indentNum == 0 {
 				ctx.addToken(token.Directive(s.pos()))
 				s.progressColumn(ctx, 1)
 				return
 			}
 		case '?':
 			nc := ctx.nextChar()
-			if ctx.bufferedSrc() == "" && nc == ' ' {
+			if !ctx.existsBuffer() && nc == ' ' {
 				ctx.addToken(token.Directive(s.pos()))
 				s.progressColumn(ctx, 1)
 				return
 			}
 		case '&':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				s.addBufferedTokenIfExists(ctx)
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.Anchor(string(ctx.obuf), s.pos()))
@@ -520,7 +521,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '*':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				s.addBufferedTokenIfExists(ctx)
 				ctx.addOriginBuf(c)
 				ctx.addToken(token.Alias(string(ctx.obuf), s.pos()))
@@ -528,7 +529,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '#':
-			if ctx.bufferedSrc() == "" || ctx.previousChar() == ' ' {
+			if !ctx.existsBuffer() || ctx.previousChar() == ' ' {
 				s.addBufferedTokenIfExists(ctx)
 				token, progress := s.scanComment(ctx)
 				ctx.addToken(token)
@@ -538,7 +539,7 @@ func (s *Scanner) scan(ctx *Context) (pos int) {
 				return
 			}
 		case '\'', '"':
-			if ctx.bufferedSrc() == "" {
+			if !ctx.existsBuffer() {
 				token, progress := s.scanQuote(ctx, c)
 				ctx.addToken(token)
 				s.progressColumn(ctx, progress)
@@ -605,7 +606,10 @@ func (s *Scanner) Scan() (token.Tokens, error) {
 		return nil, io.EOF
 	}
 	ctx := newContext(s.source[s.sourcePos:])
+	defer ctx.release()
 	progress := s.scan(ctx)
 	s.sourcePos += progress
-	return ctx.tokens, nil
+	var tokens token.Tokens
+	tokens = append(tokens, ctx.tokens...)
+	return tokens, nil
 }