deploy: cdfb130fa6

features/performance.md

@@ -27,9 +27,13 @@ A `#!cpp std::istream` (including `#!cpp std::ifstream`) gets the same bulk scan
 characters its stream buffer already holds (the *get area*) and asks the stream buffer for more only when they are used
 up. Nothing is read ahead, so the stream is left exactly where it would be after reading one character at a time, and
 [`operator>>`](../api/operator_gtgt.md) can still read several values from one stream. A stream buffer without a get
-area is read one character at a time. A `#!cpp FILE*` is locked once per parse instead of once per character, and with
-glibc and the Apple C library, the characters in its buffer are scanned in bulk as a stream's get area is. See
-[input sources and performance](parsing/index.md#input-sources-and-performance) for the full table. Parsing from a
+area is read one character at a time. Where the C library has unlocked stdio functions, a `#!cpp FILE*` is locked once
+per parse instead of once per character, and with glibc and the Apple C library, the characters in its buffer are
+scanned in bulk as a stream's get area is.
+[`JSON_DISABLE_STREAM_BULK_SCAN`](../api/macros/json_disable_stream_bulk_scan.md) turns off the bulk scan of streams, and
+[`JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md) both the single lock and the bulk scan
+of a `#!cpp FILE*`. See [input sources and performance](parsing/index.md#input-sources-and-performance) for the full
+table. Parsing from a
 stream takes about 1.15 to 1.45 times as long as parsing an equivalent `#!cpp std::string`, which `parse()` reads with
 a parser of its own (see there).