2 files changed, 28 insertions, 0 deletions
diff --git a/src/encoding/csv/reader.go b/src/encoding/csv/reader.go
index d9432954ac..d0a09044fb 100644
--- a/src/encoding/csv/reader.go
+++ b/src/encoding/csv/reader.go
@@ -228,6 +228,12 @@ func (r *Reader) parseRecord() (fields []string, err error) {
 	}
 	r.r.UnreadRune()
 
+	// If FieldsPerRecord is greater then 0 we can assume the final
+	// length of fields to be equal to FieldsPerRecord.
+	if r.FieldsPerRecord > 0 {
+		fields = make([]string, 0, r.FieldsPerRecord)
+	}
+
 	// At this point we have at least one field.
 	for {
 		haveField, delim, err := r.parseField()
diff --git a/src/encoding/csv/reader_test.go b/src/encoding/csv/reader_test.go
index 123df06bc8..b3c4f3bf18 100644
--- a/src/encoding/csv/reader_test.go
+++ b/src/encoding/csv/reader_test.go
@@ -282,3 +282,25 @@ func TestRead(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkRead(b *testing.B) {
+	data := `x,y,z,w
+x,y,z,
+x,y,,
+x,,,
+,,,
+"x","y","z","w"
+"x","y","z",""
+"x","y","",""
+"x","","",""
+"","","",""
+`
+
+	for i := 0; i < b.N; i++ {
+		_, err := NewReader(strings.NewReader(data)).ReadAll()
+
+		if err != nil {
+			b.Fatalf("could not read data: %s", err)
+		}
+	}
+}