- _clib_memcpy (&f->data[f->head], data, first_chunk);
- _clib_memcpy (&f->data[0], data + first_chunk, len - first_chunk);
+ clib_memcpy_fast (&f->data[f->head], data, first_chunk);
+ clib_memcpy_fast (&f->data[0], data + first_chunk, len - first_chunk);