That Time My Senpai Created A Catalog Page That Took Forever To Load

That Time My Senpai Created A Catalog Page That Took Forever To Load

So basically the title is the summarize of this post. The title is intended to sounds like many long light novel title. The reason I want to write this post is because there will be Comifuro this weekend. Then I remember one story from my friend about the Comifuro website.

For disclaimer, this story might be not accurate and maybe I forget some detail about it.

Flashback Story

I have a friend, we can call him ‘VC’, and meet him in my first year of my college. He is a third year student when we met.

At the day when we first met, he told me that he created a new Comifuro website for that year. At that time, the event was already over and I also attended it but never checked the Comifuro website itself.

The website itself was just standard wordpress site. He got the job to create new design and implement it as wordpress theme. He also had to create a new catalog page with some basic search function.

And here is the interesting things that he told and I still remember about it until now. He had no database access to the site so he did some workaround to create the catalog page without database.

He created new wordpress page with custom theme for that page only. Then he uploaded the CSV data to wordpress theme folder and then fetched and parsed that CSV data on the front-end using javascript.

He told me, if you open the catalog page, there was no pagination on that page and all of the images was fetched synchronously. So it would take forever to wait until the page was fully loaded.

At least he got the job done and that catalog page is functional.

Hunting The Source Code

Now, because I remember about this story, I decide to hunting the source code of the website at that time. Fortunately, I can get it from web archive, so let’s get into it.

Start with finding the right snapshot of the comifuro website in the web archive. Then I choose this Comifuro website snapshot right at second day of the event that time.

I tried to inspect this home page first and hope to get something interesting. And… I found two things.

The first one is this comment about thanks to w3school.

Thanks w3school comment
never forget to say thank you

I assume this is about the carousel code bellow this comment. So I check the bootstrap carousel page in w3school and compare them. And yes they are the same code.

comparison between two code
Left: Code from inspect element. Right: Code from w3school. Why even bother to remove the comment?

The second one is at near the bottom of the source code.

stackoverflow reference
Centering div is hard

Yep, that’s right! It’s a reference for how to center a div in stackoverflow. I know everyone is struggling to do this simple thing.

Even after discover this two things, still there is no evidence wheter this is my friend’s code or not. So let’s get into my main objective, the catalog page. Just single from main navigation at the top. I get into this snapshot of web catalog page.

As expected, the page is loading forever.

And after some digging in dev tools, finally I get this.

real game
What kind of game is this?

So, let’s take a look of this code. You can see the full code from this gist

The first block of the code is confirmed the story about the data is fetched from CSV file (and the file itself is part of wordpress theme).

$(document).ready(function () {
    type: "GET",
    url: "",
    dataType: "text",
    success: function (data) {

Here is the original result of the csv file. And this is the table view after some magic using column -s, -t < circle.csv | less -N -S command.

As you can see this CSV file is the ‘database’ for this catalog page.

Next block of the code is also interesting.

/* Showing all circles = O(n^2+n), kek */
function processData(allText) {
  var allTextLines = allText.split(/\r\n|\n/);
  var headers = allTextLines[0].split(",");
  var lines = [];

  for (var i = 1; i < allTextLines.length; i++) {
    var data = allTextLines[i].split(",");
    if (data.length == headers.length) {
      var tarr = [];
      for (var j = 0; j < headers.length; j++) {
  showAllGrid(lines); // Show in Grid (No Pagination)

So this is the main bottleneck code of this page. It loads all of the data without pagination in O(n^2+n) complexity (or O(n^2) because we can ignore the second n term).

The next bad things about this catalog page without pagination is all of the image is not compressed and fetched synchronously. So the page will be loading forever until it loads all of the images.

The visitors of Comifuro at that time is supposed to access this catalog page if they want to browse and search online. Just imagine they open this page via mobile browser inside the building with bad internet signal, how long it will take until the page is usable to browse and search.

Doing Some Experiments

So I want to measure how long until the page is fully load. I’m using networking dev tools in firefox to get the exact time.

My home internet connection is about 2 MB/s. Let’s see the result!

firefox blank
First try the page does not show anything.

firefox result blank
Thousand requests!


I try once again to fully reload the page with ctrl + alt + R. This time it shows the catalog content.

firefox load
Finally it's fully loaded!

firefox result load
Looks the same with previous 'blank' result

Based on the two tries above. The page and its resource are fully fetched for about 2 minutes with my connection. It makes about thousand requests and download about 150 MB resources.

Not too bad.

With raw calculation, 150 MB / 2 MB/s = 75 s. 75 seconds or 1.25 minutes, a bit far from 1.89 minutes in real result.

Once again I open the catalog with different browser. I’m using chromium this time.

chromium load
This time it's fully loaded for the first time

chromium result
Different result with firefox

I don’t know what happened, but chromium loads very slow for about 6 minutes. The result is very far from firefox. Still the same about thousand requests but it downloads only about 75 MB resources.

Maybe because I’ve open the page in firefox before so some of the resouces are loaded from cache. Or maybe because external factor like the web archive itself is slow. But another weird thing is chromium only fetchs 75 MB compare to firefox with 150 MB resources. Honestly I dont know ¯\_(ツ)_/¯

Well I don’t want to thing about it now. But the thing that I want to check is the page is loaded very slow. Maybe it was unusable for use case that I mention before. Visitors open the catalog page using mobile browser inside the building with bad internet signal.

At least the search function is implemented in front-end. So after the page is loaded, you don’t have to wait again to see the search result.


Now I check the current catalog page, it’s far better than this very bad catalog page. In fact the next iteration of catalog page that I found in this snapshot is already better by load all images asynchronously.

The current catalog page is very fast. It also has button to save the assets catalog offline. The visitors can just download it on mobile browser it before the event and then access it later.

offline assets

I will be attending this event on this weekend to meet with my friends. But I anticipate there will be so many visitors because this is the first offline Comifuro event after two years of quarantine and also there’s meet and greet event with vtuber agency in this event. And for makes things worse, there’s also K-Pop concert at the same place with Comifuro. It means there will be sea of people there.

I hope I can survived.

Fun fact: the Comifuro 10 is announced and marketed as CFX. At the same year, there’s also COMPFEST X event and its branding is also CFX.