Potential workaround for poor zstd performance

Performance is still not great, but better

internal/decompress/lz4.go

@@ -11,3 +11,10 @@ type Lz4 struct{}
 func (l Lz4) Reader(r io.Reader) (io.ReadCloser, error) {
 	return io.NopCloser(lz4.NewReader(r)), nil
 }
+
+func (l Lz4) Resetable() bool { return true }
+
+func (l Lz4) Reset(old, src io.Reader) error {
+	old.(*lz4.Reader).Reset(src)
+	return nil
+}