diff --git a/internal/encoding/wire/wire.go b/internal/encoding/wire/wire.go
index 32622b1..d7baa7f 100644
--- a/internal/encoding/wire/wire.go
+++ b/internal/encoding/wire/wire.go
@@ -176,7 +176,6 @@
 
 // AppendVarint appends v to b as a varint-encoded uint64.
 func AppendVarint(b []byte, v uint64) []byte {
-	// TODO: Specialize for sizes 1 and 2 with mid-stack inlining.
 	switch {
 	case v < 1<<7:
 		b = append(b, byte(v))
@@ -259,7 +258,6 @@
 // ConsumeVarint parses b as a varint-encoded uint64, reporting its length.
 // This returns a negative length upon an error (see ParseError).
 func ConsumeVarint(b []byte) (v uint64, n int) {
-	// TODO: Specialize for sizes 1 and 2 with mid-stack inlining.
 	var y uint64
 	if len(b) <= 0 {
 		return 0, errCodeTruncated
diff --git a/internal/impl/decode.go b/internal/impl/decode.go
index fc93525..4a1d631 100644
--- a/internal/impl/decode.go
+++ b/internal/impl/decode.go
@@ -97,15 +97,27 @@
 	start := len(b)
 	for len(b) > 0 {
 		// Parse the tag (field number and wire type).
-		// TODO: inline 1 and 2 byte variants?
-		num, wtyp, n := wire.ConsumeTag(b)
-		if n < 0 {
-			return out, wire.ParseError(n)
+		var tag uint64
+		if b[0] < 0x80 {
+			tag = uint64(b[0])
+			b = b[1:]
+		} else if len(b) >= 2 && b[1] < 128 {
+			tag = uint64(b[0]&0x7f) + uint64(b[1])<<7
+			b = b[2:]
+		} else {
+			var n int
+			tag, n = wire.ConsumeVarint(b)
+			if n < 0 {
+				return out, wire.ParseError(n)
+			}
+			b = b[n:]
 		}
-		if num > wire.MaxValidNumber {
+		num := wire.Number(tag >> 3)
+		wtyp := wire.Type(tag & 7)
+
+		if num < wire.MinValidNumber || num > wire.MaxValidNumber {
 			return out, errors.New("invalid field number")
 		}
-		b = b[n:]
 
 		if wtyp == wire.EndGroupType {
 			if num != groupTag {
@@ -121,6 +133,7 @@
 		} else {
 			f = mi.coderFields[num]
 		}
+		var n int
 		err := errUnknown
 		switch {
 		case f != nil: