A.java

private static final ObjectMapper OM = new ObjectMapper();

@Benchmark
public void jsonStringSerialization(final Blackhole blackhole) throws Exception {
    byte[] obj = OM.writeValueAsBytes(randomString());
    blackhole.consume(new String(obj, 1, obj.length - 2, StandardCharsets.UTF_8));
}

@Benchmark
public void jsonStringManual(final Blackhole blackhole) {
    String str = randomString();
    if (str.contains("\\")) {
        str = str.replace("\\", "\\\\");
    }
    if (str.contains("\"")) {
        str = str.replace("\"", "\\\"");
    }
    blackhole.consume(str);
}

private static String randomString() {
    return RandomStringUtils.random(75,
            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
            'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
            'y', 'z',
            '\\', '\r', '\n', '\"', '\'', ' ');
}

@Benchmark
public void randomString(final Blackhole blackhole) {
    blackhole.consume(randomString());
}