update benchmark results

Author: gfx

README.md

@@ -517,21 +517,20 @@ V8's built-in JSON has been improved for years, esp. `JSON.parse()` is [signific
 
 However, MessagePack can handles binary data effectively, actual performance depends on situations. You'd better take benchmark on your own use-case if performance matters.
 
-Benchmark on NodeJS/v12.18.3 (V8/7.8)
+Benchmark on NodeJS/v18.1.0 (V8/10.1)
 
 operation                                                         |   op   |   ms  |  op/s
 ----------------------------------------------------------------- | ------: | ----: | ------:
-buf = Buffer.from(JSON.stringify(obj));                           |  840700 |  5000 |  168140
-buf = JSON.stringify(obj);                                        | 1249800 |  5000 |  249960
-obj = JSON.parse(buf);                                            | 1648000 |  5000 |  329600
-buf = require("msgpack-lite").encode(obj);                        |  603500 |  5000 |  120700
-obj = require("msgpack-lite").decode(buf);                        |  315900 |  5000 |   63180
-buf = require("@msgpack/msgpack").encode(obj);                    |  945400 |  5000 |  189080
-obj = require("@msgpack/msgpack").decode(buf);                    |  770200 |  5000 |  154040
-buf = /* @msgpack/msgpack */ encoder.encode(obj);                 | 1162600 |  5000 |  232520
-obj = /* @msgpack/msgpack */ decoder.decode(buf);                 |  787800 |  5000 |  157560
-
-Note that `Buffer.from()` for `JSON.stringify()` is necessary to emulate I/O where a JavaScript string must be converted into a byte array encoded in UTF-8, whereas MessagePack's `encode()` returns a byte array.
+buf = Buffer.from(JSON.stringify(obj));                           |  902100 |  5000 |  180420
+obj = JSON.parse(buf.toString("utf-8"));                          |  898700 |  5000 |  179740
+buf = require("msgpack-lite").encode(obj);                        |  411000 |  5000 |   82200
+obj = require("msgpack-lite").decode(buf);                        |  246200 |  5001 |   49230
+buf = require("@msgpack/msgpack").encode(obj);                    |  843300 |  5000 |  168660
+obj = require("@msgpack/msgpack").decode(buf);                    |  489300 |  5000 |   97860
+buf = /* @msgpack/msgpack */ encoder.encode(obj);                 | 1154200 |  5000 |  230840
+obj = /* @msgpack/msgpack */ decoder.decode(buf);                 |  448900 |  5000 |   89780
+
+Note that `JSON` cases use `Buffer` to emulate I/O where a JavaScript string must be converted into a byte array encoded in UTF-8, whereas MessagePack modules deal with byte arrays.
 
 ## Distribution