diff --git a/encode.go b/encode.go
index 46c7ec0..f6fd255 100644
--- a/encode.go
+++ b/encode.go
@@ -2,6 +2,7 @@ package tblfmt
 
 import (
 	"bufio"
+	"bytes"
 	"encoding/csv"
 	"encoding/json"
 	"fmt"
@@ -39,6 +40,9 @@ type TableEncoder struct {
 	// lineStyle is the table line style.
 	lineStyle LineStyle
 
+	// rowStyles is the table of row style.
+	rowStyles map[[4]rune]rowStyle
+
 	// formatter handles formatting values prior to output.
 	formatter Formatter
 
@@ -94,6 +98,7 @@ func NewTableEncoder(resultSet ResultSet, opts ...Option) (Encoder, error) {
 		border:    1,
 		tab:       8,
 		lineStyle: ASCIILineStyle(),
+		rowStyles: make(map[[4]rune]rowStyle),
 		formatter: NewEscapeFormatter(WithHeaderAlign(AlignCenter)),
 		summary:   DefaultTableSummary(),
 		empty: &Value{
@@ -117,6 +122,7 @@ func NewTableEncoder(resultSet ResultSet, opts ...Option) (Encoder, error) {
 		enc.lineStyle.Wrap,
 		enc.lineStyle.End,
 	} {
+		enc.rowStyles[l] = enc.rowStyle(l)
 		for _, r := range l {
 			if r != 0 && runewidth.RuneWidth(r) != 1 {
 				return nil, ErrInvalidLineStyle
@@ -214,7 +220,7 @@ func (enc *TableEncoder) Encode(w io.Writer) error {
 
 		// draw end border
 		if enc.border >= 2 {
-			enc.divider(enc.rowStyle(enc.lineStyle.End))
+			enc.divider(enc.rowStyles[enc.lineStyle.End])
 		}
 	}
 
@@ -239,7 +245,7 @@ func (enc *TableEncoder) initBuffers() {
 }
 
 func (enc *TableEncoder) encodeVals(vals [][]*Value) error {
-	rs := enc.rowStyle(enc.lineStyle.Row)
+	rs := enc.rowStyles[enc.lineStyle.Row]
 	// print buffered vals
 	for i := 0; i < len(vals); i++ {
 		enc.row(vals[i], rs)
@@ -308,7 +314,7 @@ func (enc *TableEncoder) nextResults() ([][]*Value, error) {
 func (enc *TableEncoder) calcWidth(vals [][]*Value) {
 	// calc offsets and widths for this batch of rows
 	var offset int
-	rs := enc.rowStyle(enc.lineStyle.Row)
+	rs := enc.rowStyles[enc.lineStyle.Row]
 	offset += runewidth.StringWidth(string(rs.left))
 	for i, h := range enc.headers {
 		if i != 0 {
@@ -339,7 +345,7 @@ func (enc *TableEncoder) calcWidth(vals [][]*Value) {
 }
 
 func (enc *TableEncoder) header() {
-	rs := enc.rowStyle(enc.lineStyle.Row)
+	rs := enc.rowStyles[enc.lineStyle.Row]
 
 	if enc.title != nil && enc.title.Width != 0 {
 		maxWidth := ((enc.tableWidth() - enc.title.Width) / 2) + enc.title.Width
@@ -348,12 +354,12 @@ func (enc *TableEncoder) header() {
 	}
 	// draw top border
 	if enc.border >= 2 && !enc.inline {
-		enc.divider(enc.rowStyle(enc.lineStyle.Top))
+		enc.divider(enc.rowStyles[enc.lineStyle.Top])
 	}
 
 	// draw the header row with top border style
 	if enc.inline {
-		rs = enc.rowStyle(enc.lineStyle.Top)
+		rs = enc.rowStyles[enc.lineStyle.Top]
 	}
 
 	// write header
@@ -361,7 +367,7 @@ func (enc *TableEncoder) header() {
 
 	if !enc.inline {
 		// draw mid divider
-		enc.divider(enc.rowStyle(enc.lineStyle.Mid))
+		enc.divider(enc.rowStyles[enc.lineStyle.Mid])
 	}
 }
 
@@ -400,14 +406,15 @@ func (enc TableEncoder) rowStyle(r [4]rune) rowStyle {
 		middle = string(r[2]) + spacer
 	}
 
-	return rowStyle{
+	rs := rowStyle{
 		left:        []byte(left),
 		wrapper:     []byte(string(enc.lineStyle.Wrap[1])),
 		middle:      []byte(middle),
 		right:       []byte(right + string(enc.newline)),
-		filler:      []byte(filler),
+		filler:      bytes.Repeat([]byte(filler), 8)[:len(filler)],
 		hasWrapping: runewidth.RuneWidth(enc.lineStyle.Row[1]) > 0,
 	}
+	return rs
 }
 
 // scanAndFormat scans and formats values from the result set.
@@ -449,7 +456,7 @@ func (enc *TableEncoder) divider(rs rowStyle) {
 
 // tableWidth calculates total table width.
 func (enc *TableEncoder) tableWidth() int {
-	rs := enc.rowStyle(enc.lineStyle.Mid)
+	rs := enc.rowStyles[enc.lineStyle.Mid]
 	width := runewidth.StringWidth(string(rs.left)) + runewidth.StringWidth(string(rs.right))
 
 	for i, w := range enc.maxWidths {
@@ -682,7 +689,7 @@ func (enc *ExpandedEncoder) Encode(w io.Writer) error {
 }
 
 func (enc *ExpandedEncoder) encodeVals(vals [][]*Value) error {
-	rs := enc.rowStyle(enc.lineStyle.Row)
+	rs := enc.rowStyles[enc.lineStyle.Row]
 	// print buffered vals
 	for i := 0; i < len(vals); i++ {
 		enc.record(i, vals[i], rs)
@@ -701,7 +708,7 @@ func (enc *ExpandedEncoder) encodeVals(vals [][]*Value) error {
 
 	// draw end border
 	if enc.border >= 2 && enc.scanCount != 0 {
-		enc.divider(enc.rowStyle(enc.lineStyle.End))
+		enc.divider(enc.rowStyles[enc.lineStyle.End])
 	}
 	return nil
 }
@@ -732,7 +739,7 @@ func (enc *ExpandedEncoder) EncodeAll(w io.Writer) error {
 }
 
 func (enc *ExpandedEncoder) calcWidth(vals [][]*Value) {
-	rs := enc.rowStyle(enc.lineStyle.Row)
+	rs := enc.rowStyles[enc.lineStyle.Row]
 
 	offset := runewidth.StringWidth(string(rs.left))
 
@@ -770,9 +777,9 @@ func (enc *ExpandedEncoder) record(i int, vals []*Value, rs rowStyle) {
 	headerRS := rs
 	header := enc.recordHeader(i)
 	if enc.border != 0 {
-		headerRS = enc.rowStyle(enc.lineStyle.Top)
+		headerRS = enc.rowStyles[enc.lineStyle.Top]
 		if i != 0 {
-			headerRS = enc.rowStyle(enc.lineStyle.Mid)
+			headerRS = enc.rowStyles[enc.lineStyle.Mid]
 		}
 	}
 
diff --git a/fmt.go b/fmt.go
index b7bc5ec..95e3d77 100644
--- a/fmt.go
+++ b/fmt.go
@@ -47,6 +47,9 @@ type EscapeFormatter struct {
 	// If nil, the standard encoding/json.Encoder will be used instead.
 	marshaler func(interface{}) ([]byte, error)
 
+	defaultMarshaler       *json.Encoder
+	defaultMarshalerBuffer *bytes.Buffer
+
 	// prefix is indent prefix used by the JSON encoder when Marshaler is nil.
 	prefix string
 
@@ -79,11 +82,15 @@ type EscapeFormatter struct {
 // values.
 func NewEscapeFormatter(opts ...EscapeFormatterOption) *EscapeFormatter {
 	f := &EscapeFormatter{
-		mask:       "%d",
-		timeFormat: time.RFC3339Nano,
-		indent:     "  ",
-		valuesPool: newValuesPool(),
+		mask:                   "%d",
+		timeFormat:             time.RFC3339Nano,
+		indent:                 "  ",
+		valuesPool:             newValuesPool(),
+		defaultMarshalerBuffer: new(bytes.Buffer),
 	}
+	f.defaultMarshaler = json.NewEncoder(f.defaultMarshalerBuffer)
+	f.defaultMarshaler.SetIndent(f.prefix, f.indent)
+	f.defaultMarshaler.SetEscapeHTML(f.escapeHTML)
 	f.Configure(opts...)
 	return f
 }
@@ -288,17 +295,15 @@ func (f *EscapeFormatter) Format(vals []interface{}) ([]*Value, error) {
 				res[i] = f.valuesPool.newRaw(buf)
 			} else {
 				// json encode
-				buf := new(bytes.Buffer)
-				enc := json.NewEncoder(buf)
-				enc.SetIndent(f.prefix, f.indent)
-				enc.SetEscapeHTML(f.escapeHTML)
-				if err := enc.Encode(v); err != nil {
+				// TODO reuse buffer and reset it before every use
+				f.defaultMarshalerBuffer.Reset()
+				if err := f.defaultMarshaler.Encode(v); err != nil {
 					return nil, err
 				}
 				if f.escapeJSON {
-					res[i] = f.valuesPool.newRaw(bytes.TrimSpace(buf.Bytes()))
+					res[i] = f.valuesPool.newRaw(bytes.TrimSpace(f.defaultMarshalerBuffer.Bytes()))
 				} else {
-					res[i] = f.valuesPool.formatBytes(bytes.TrimSpace(buf.Bytes()), f.invalid, f.invalidWidth, false)
+					res[i] = f.valuesPool.formatBytes(bytes.TrimSpace(f.defaultMarshalerBuffer.Bytes()), f.invalid, f.invalidWidth, false)
 					res[i].Raw = true
 				}
 			}
diff --git a/go.mod b/go.mod
index ffe21c8..4ad9c6b 100644
--- a/go.mod
+++ b/go.mod
@@ -1,7 +1,7 @@
 module github.com/xo/tblfmt
 
 require (
-	github.com/mattn/go-runewidth v0.0.9
+	github.com/mattn/go-runewidth v0.0.10
 	github.com/nathan-fiscaletti/consolesize-go v0.0.0-20210105204122-a87d9f614b9d
 )
 
diff --git a/go.sum b/go.sum
index 7905545..168c338 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +1,6 @@
-github.com/mattn/go-runewidth v0.0.9 h1:Lm995f3rfxdpd6TSmuVCHVb/QhupuXlYr8sCI/QdE+0=
-github.com/mattn/go-runewidth v0.0.9/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
+github.com/mattn/go-runewidth v0.0.10 h1:CoZ3S2P7pvtP45xOtBw+/mDL2z0RKI576gSkzRRpdGg=
+github.com/mattn/go-runewidth v0.0.10/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
 github.com/nathan-fiscaletti/consolesize-go v0.0.0-20210105204122-a87d9f614b9d h1:PQW4Aqovdqc9efHl9EVA+bhKmuZ4ME1HvSYYDvaDiK0=
 github.com/nathan-fiscaletti/consolesize-go v0.0.0-20210105204122-a87d9f614b9d/go.mod h1:cxIIfNMTwff8f/ZvRouvWYF6wOoO7nj99neWSx2q/Es=
+github.com/rivo/uniseg v0.1.0 h1:+2KBaVoUmb9XzDsrx/Ct0W/EYOSFf/nWTauy++DprtY=
+github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
diff --git a/util.go b/util.go
index b3649ad..6f47c57 100644
--- a/util.go
+++ b/util.go
@@ -114,10 +114,10 @@ func repeat(w io.Writer, b []byte, c int) []byte {
 		w.Write(b[:c])
 		return b
 	}
-	nb := b[:cap(b)]
-	for len(nb) < c {
-		nb = append(nb, nb...)
+	b = b[:cap(b)]
+	for len(b) < c {
+		b = append(b, b...)
 	}
-	w.Write(nb[:c])
-	return nb[:len(b)]
+	w.Write(b[:c])
+	return b[:1]
 }