console.log is slow

The real reason behind this is that console.log is actually synchronous and mixing sync with async is pretty bad in any language or runtime. People should use something like opentelemetry-js or other telemetry tools for logging instead of console.logs.

Because console in chrome is DOM and every line is a new element, so console.log is roughly equivalent to

let line = document.createElement("div");
for(let item of args) {  
   if (item !== null && typeof item === "object") {
       let segment = document.createElement("span");
       // little carat to open and show element
       segment.class = "drop-down"
       // some sort of expanding object children
       segment.addEventListener("click",
          () => createChildren(item)   });
          // also create some child elements to display few properties... 
          // change class if its an array etc...
          ...
          ...
       continue;
   }
   line.appendChild(document.createTextNode(item.toString()));
}
consoleElement.appendChild(line);
line.scrollIntoView();

Damn sure enough, it's pretty slow.

10000 rows.

with console
422.90000000596046
410.90000000596046
437.30000001192093

without
0.30000001192092896
0.4000000059604645
0.10000002384185791

Makes sense. I/O operations are slow (even if it's just output on the screen.)

Try to reduce the amount of data that is stored in the console.log, also use session store instead of file.
with the definition set as needed here

EXAMPLE:
// Save element position
app.post('/position', (req, res) => {
const positionData = req.body;
const elementId = positionData.elementId;
const sessionData = req.session;

// Update the session data with the new position data for the element
sessionData[elementId] = positionData;

// Return a success status code
res.sendStatus(200);
});

Displaying a console.log in a terminal is super slow period.

now i'm curious. What numbers did you see?

How did you get it ?
You got me curious. Show us plz

This is intentional, the Node.js docs say:

A note on process I/O#
process.stdout and process.stderr differ from other Node.js streams in important ways:

They are used internally by console.log() and console.error(), respectively.
Writes may be synchronous depending on what the stream is connected to and whether the system is Windows or POSIX:
Files: synchronous on Windows and POSIX
TTYs (Terminals): asynchronous on Windows, synchronous on POSIX
Pipes (and sockets): synchronous on Windows, asynchronous on POSIX
These behaviors are partly for historical reasons, as changing them would create backward incompatibility, but they are also expected by some users.

Synchronous writes avoid problems such as output written with console.log() or console.error() being unexpectedly interleaved, or not written at all if process.exit() is called before an asynchronous write completes. See process.exit() for more information.

Might be good to show some examples... stackoverflow.com/a/26754011/21061 gives a nice breakdown with evidence...

Checkout this

How a single line code change, improved my performance

MR.H ・ Feb 26 ・ 2 min read

#beginners #javascript #programming #webdev

You're causing a write operation, which is inherently blocking. Buffer your output or don't have any at all when it's performance critical.

It's like cout in C++. You shouldn't really use both cout and console.log if you're looking for performance in the console.