diff --git a/common/bootcommand/boot_command.go b/common/bootcommand/boot_command.go
index 1447a4337..b16864e42 100644
--- a/common/bootcommand/boot_command.go
+++ b/common/bootcommand/boot_command.go
@@ -13,6 +13,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 	"unicode"
 	"unicode/utf8"
@@ -981,7 +982,7 @@ type position struct {
 }
 
 func (p position) String() string {
-	return fmt.Sprintf("%d:%d [%d]", p.line, p.col, p.offset)
+	return strconv.Itoa(p.line) + ":" + strconv.Itoa(p.col) + " [" + strconv.Itoa(p.offset) + "]"
 }
 
 // savepoint stores all state required to go back to this point in the
@@ -1445,13 +1446,24 @@ type Cloner interface {
 	Clone() interface{}
 }
 
+var statePool = &sync.Pool{
+	New: func() interface{} { return make(storeDict) },
+}
+
+func (sd storeDict) Discard() {
+	for k := range sd {
+		delete(sd, k)
+	}
+	statePool.Put(sd)
+}
+
 // clone and return parser current state.
 func (p *parser) cloneState() storeDict {
 	if p.debug {
 		defer p.out(p.in("cloneState"))
 	}
 
-	state := make(storeDict, len(p.cur.state))
+	state := statePool.Get().(storeDict)
 	for k, v := range p.cur.state {
 		if c, ok := v.(Cloner); ok {
 			state[k] = c.Clone()
@@ -1468,6 +1480,7 @@ func (p *parser) restoreState(state storeDict) {
 	if p.debug {
 		defer p.out(p.in("restoreState"))
 	}
+	p.cur.state.Discard()
 	p.cur.state = state
 }
 
@@ -1580,7 +1593,7 @@ func listJoin(list []string, sep string, lastSep string) string {
 	case 1:
 		return list[0]
 	default:
-		return fmt.Sprintf("%s %s %s", strings.Join(list[:len(list)-1], sep), lastSep, list[len(list)-1])
+		return strings.Join(list[:len(list)-1], sep) + " " + lastSep + " " + list[len(list)-1]
 	}
 }
 
@@ -1880,7 +1893,7 @@ func (p *parser) parseLitMatcher(lit *litMatcher) (interface{}, bool) {
 	if lit.ignoreCase {
 		ignoreCase = "i"
 	}
-	val := fmt.Sprintf("%q%s", lit.val, ignoreCase)
+	val := string(strconv.AppendQuote([]byte{}, lit.val)) + ignoreCase // wrap 'lit.val' with double quotes
 	start := p.pt
 	for _, want := range lit.val {
 		cur := p.pt.rn