page loading really slow

[Fargus-Van-Crystal-de-Mindark]

Hello Tim, I hope you are well. Unfortunately, I have some bad news to report. The latest updates to YT Alchemy have made page loading really slow. The home page won't load, and switching between pages has become truly unbearable.
The options you've added are great, but you should also take it easy with the additions. Bear in mind that I'm forced to disable the extension in order to be able to watch a video.

Could you do something about it? Thanks in advance.

[TimMacy]

Hey! Thanks for reporting this. That's definitely not the experience you should be having.

To help track this down, could you share a bit more info?

• Which version was working fine before?
• Are you using the userscript or browser extension?
• What browser and device are you on?
• Have you tried disabling other extensions or userscripts to rule out conflicts?
• Have you tried resetting the settings back to default and does the problem persist?

If you're on the userscript, try the browser extension as it's generally faster and more stable. Also, the latest updates were minor tweaks and improvements which shouldn't have impacted the performance, and I'm not having any issues on my end.

[Fargus-Van-Crystal-de-Mindark]

Hello Tim, thanks a lot for your hard work and I hope to find a solution with you about this ♥

So, about your questions :

1. I'm sure it was version 9.0.2 that was the last one to work correctly for me. I remember exactly that it was from this time that I stopped following the updates. I let it update automatically without paying attention.
2. Userscript with tampermonkey
3. Chrome Version 143.0.7499.110 (Build officiel) (64 bits) on Windows 11
4. no, I didn't
5. no, I didn't

Ok so you definitely suggest to try the extension and that it is (or should) be better than the userscript?

[TimMacy]

The userscript's and browser extension's core logic are the same, they just run in a different environment. The extension removes the middleman (Tampermonkey) and utilizes Chrome's own extension system, which injects the CSS as a real stylesheet, instead of being generated with JavaScript and parsed as <style> text at runtime on each page load. Also, extensions are pre-parsed/cached when enabled to run the code more effectively than a userscript manager, which injects the code dynamically.

My suggestion: Export your settings first (if you haven't already), disable the userscript, install the browser extension, and test it. If it works fine, import your settings and have another look.
If the problem persists, check if any other extensions, userscripts, or adblockers might interfere with it.

[Fargus-Van-Crystal-de-Mindark]

Update Summary

Following Tim’s suggestions and troubleshooting steps, I’ve conducted several tests to narrow down the issue related to slow page loading in YouTube Alchemy. Below are the latest findings and configurations used during testing.

---

Configuration

• Version previously working fine: 9.0.2
• Current setup: Browser extension (YouTube Alchemy Extension)
• Previous setup: Userscript with Tampermonkey
• Browser: Google Chrome Version 143.0.7499.110 (Official Build) (64-bit)
• Operating System: Windows 11
• VPN: Disabled
• Browser extensions currently enabled: NordPass only
• Other extensions/userscripts: Disabled during test
• Settings import: Tested both with and without imported settings

---

Issue Description

After switching from the userscript to the browser extension as suggested, the performance issue persists on specific YouTube pages:

• Home page
• Subscriptions page

Both pages experience significant delays when loading or switching. Other pages appear to perform normally.

---

Steps Taken

1. Disabled all browser extensions except NordPass.
2. Disabled the YouTube Alchemy userscript from Tampermonkey.
3. Installed and enabled the YouTube Alchemy Chrome extension.
4. Tested performance with default settings.
5. Tested performance again after importing previous custom settings.
6. Tested with errors logs enabled.

---

Current Results

• The issue persists under both default and imported settings.
• Performance degradation occurs mainly when browsing the Home and Subscriptions pages.
• Other parts of YouTube seem unaffected.
• No errors logs detected.

---

Next Steps / Request for Support

Could you please check if there’s any recent change that might have affected CSS injection or runtime scripts specifically on those two pages? I’d be happy to provide console logs or inspect specific elements if that would help diagnose further.

[TimMacy]

If you're saying that 9.0.2 worked fine, I'm assuming the issues started with 9.1? But that only changed some CSS (mainly fullscreen adjustments and for video pages), added the compact version for remaining time, and adjusted the fullscreen EventListener for the tabView function.

There are two functions running on both the Home and Subscription pages that could cause it. Please go to Color Code Videos and turn off both Color Code Videos Based on Age and Status and Color Code Last Uploaded Video.
Do you still have to disable the script on video pages in order to watch videos?
Did you disable an ad blocker if you're using one?

[Fargus-Van-Crystal-de-Mindark]

the problem persist. I give you my configuration.

YouTube-Alchemy_v9.6.1_Backup_2025-12-12T21-58-26-873Z.json

[TimMacy]

Install version 9.1, the version where you first noticed the problem. Then disable features one by one and check when the performance improves. You can disable everything except the Settings button. That should help narrow down which part of the script is causing the issue for you.

[dobisskill]

I have also been experiencing extremely slow loading on the home and subscriptions pages. I deselected every option and started re-enabling things one by one, and it seems to be "Custom Selection Color" that's causing the issue in my case. With it disabled, the page loads perfectly. When enabled, the pages become unresponsive. I also noticed that if the pages do load properly, the page will still hang when you click this 3 dot menu:

[TimMacy]

What do you mean by "hang"? If you mean you can't scroll, that's YouTube preventing that.
As for the Custom Selection Color issue, I looked at the code and it looks fine, and since I can't reproduce it on my end, I'd recommend keeping it disabled for now.

[dobisskill]

By “hang” I just meant that clicking it makes the page unresponsive, and shortly after Chrome brings up a dialog box to either wait or exit the page. It only seems to happen with the custom selection color option enabled. I’ve had it disabled since my last post and everything else has been working flawlessly so I’ll keep it disabled for now.

[Fargus-Van-Crystal-de-Mindark]

@dobisskill Initially, I also thought that "Custom Selection Color" was the loading problem. Yes, it reduces the problem somewhat. But it doesn't remove it.

@TimMacy How is it possible that you don't encounter this problem? I also tried changing my geographical location by connecting to different internet networks. I tried disabling the VPN and using YouTube Alchemy on another computer. But the problem seems to be common regardless of the device or network used.
Honestly, there is nothing I can do (change settings) that can solve this. I wonder: is it possible that YouTube has made changes to the home page and subscription page that are causing these significant slowdowns? Slowdowns that even cause the page to freeze. It is my habit to keep everything extremely up to date with the latest version. So, it could be.... I don't know.

Hope that you will find a solution in the future.

[TimMacy]

You could try running this test build and check the console logs. Filter for "YouTubeAlchemy" and you should see something like this:

YouTubeAlchemy: CSS: 1ms - timer ended YouTube-Alchemy.user.js:4883:9
YouTubeAlchemy: Config: 0ms - timer ended YouTube-Alchemy.user.js:5138:9
YouTubeAlchemy: loadCSSsettings: 0ms - timer ended YouTube-Alchemy.user.js:5289:9
YouTubeAlchemy: total: 1ms - timer ended YouTube-Alchemy.user.js:11273:13
YouTubeAlchemy: Event Listner Arrived YouTube-Alchemy.user.js:11200:17
YouTubeAlchemy: Only One Survived YouTube-Alchemy.user.js:11204:21
YouTubeAlchemy: handleYouTubeNavigation: 0ms - timer ended YouTube-Alchemy.user.js:11245:69
YouTubeAlchemy: Event Listner Arrived 2 YouTube-Alchemy.user.js:11200:17
YouTubeAlchemy: initializeAlchemy: 0ms - timer ended YouTube-Alchemy.user.js:11195:9

If one of those lines shows a much higher time, that might help narrow down where the slowdown happens.
Heads-up: this debug version disables all features on purpose, and you can't change that in the settings panel. Also, your userscript manager should be able to auto-update it back to the current public version.

YouTube-Alchemy_9.13-test1.user.js .js

[dobisskill]

This is what I'm getting from the logs on the test version;

YouTubeAlchemy: CSS: 0.35986328125 ms
YouTube Alchemy.user.js:5137 YouTubeAlchemy: Config: 14.961181640625 ms
YouTube Alchemy.user.js:5288 YouTubeAlchemy: loadCSSsettings: 2.215087890625 ms
YouTube Alchemy.user.js:11276 YouTubeAlchemy: total: 35.61181640625 ms
YouTube Alchemy.user.js:11199 YouTubeAlchemy: Event Listner Arrived
YouTube Alchemy.user.js:11203 YouTubeAlchemy: Only One Survived
YouTube Alchemy.user.js:11199 YouTubeAlchemy: Event Listner Arrived
YouTube Alchemy.user.js:11199 YouTubeAlchemy: Event Listner Arrived
YouTube Alchemy.user.js:11194 YouTubeAlchemy: initializeAlchemy: 2.385986328125 ms

[TimMacy]

Thanks for testing it. Those timings are still tiny, so the script loads fine and it doesn't explain why the Home page becomes unresponsive. Just to confirm, even with the test build the Home page still freezes? If yes, the next quick test is to rule out CSS injection.

In the test script, find the CSS timing block and remove those two lines and everything in between:

console.time("YouTubeAlchemy: CSS");
. . .
. . .
. . .
console.timeEnd("YouTubeAlchemy: CSS");

After removing that block, the top of the script should look like this:

(async function () {
    'use strict';
    console.time("YouTubeAlchemy: total");
    // CSS
    console.time("YouTubeAlchemy: Config");
    // default configuration
    const DEFAULT_CONFIG = {

Then reload YouTube and test the Home page again to see whether the performance changes.

[Fargus-Van-Crystal-de-Mindark]

It's getting too technical. I can't help you any further because I don't have the expertise. I'll let other users collaborate on the testing, but I'll continue to actively follow the development and conversation.