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WP Parallel Loading System icon
Possibly abandoned Tested up to 3.0.5 #68 in image optimization

WP Parallel Loading System

If you have an image intensive Blog, or even if you don’t, this plugin will boost the loading time of your Blog. The more images you have the more it will improve.

Active installs20+10+ tier
Downloads · 30d48▼ -11.1% vs prev. 30d
Rating2.7/53 reviews
Health score24/100At risk
All-time downloads20.6KSince May 2010
Support resolved—No recent threads
RequiresWP 2.9.0PHP any
Downloads · 7d9▼ -10% week over week
Our verdict

Consider an alternative

WP Parallel Loading System shows warning signs in 2026 — compare the alternatives below before installing. It runs on 20+ sites, is rated 2.7/5 and was last updated 16 years ago, and scores 24/100 on our health check.

  • Small user base (20+ active installs)
  • Low rating so far — 2.7/5 from only 3 reviews
  • No update in 15 years
  • Only tested up to WordPress 3.0 (latest is 7.1)

How does it stack up?

Side-by-side on installs, updates, ratings & support

Daily downloads

4812Jul 1Aug 14Sep 28
Yesterday1
Daily average (1y)1
Peak day16Aug 26, 2026
Last 12 months513

Download spikes usually follow a new release — each site that auto-updates counts as a download.

Rankings

Where WP Parallel Loading System stands today

WordPress.org search rankings

Live position in the plugin search, top 100
KeywordPositionCompeting pluginsCategory
image optimization >100 2,945 Best image optimization plugins →
loading >100 9,803 Best loading plugins →
parallel >100 289 Best parallel plugins →
seo >100 8,245 Best seo plugins →
speed improve >100 2,006 Best speed improve plugins →

Version adoption

Share of active sites per release.

  • 0.1100.0%

Rating breakdown

★★★★★★★★★★ 2.7 from 3 reviews

  • 5★33.3%
  • 4★0.00%
  • 3★0.00%
  • 2★33.3%
  • 1★33.3%

About WP Parallel Loading System

From the official readme · v0.1.9.1

Description

Why use it?

If you have an image intensive Blog, or even if you don’t, this plugin will boost the loading time of your Blog. The more images you have the more it will improve.

The amount of people that will visit your website for the first time or visit with an empty cache or disabled cache is huge, therefore, the best your website performs on that first visit the more chances that person will remain to view your website.

It is also known that nowadays, Google (and other search engines), are taking into account, for ranking purposes, your website page speed. Google Bot does not conserve a cache when it visits your website, so, the faster your website loads the more chances you have to rank higher.

This plug will not change anything on your Blogs Posts. Every change that it makes will be processed in real time, right before the HTML code of your Blog is sent to the browser.
There are however some changes needed on a few files, but the plugin will attempt to do everything by himself without causing harm to your files. For every file that he changes a backup is created, therefore, at any time, you can revert the changes back!

How does it work?

Standard HTTP v1.1 requests only allow 2 connections, at the same time, from the same domain.

This plugin will virtualize connections, through defined subdomains. You can have as many subdomains as you like, but I do recommend using a maximum of 5.

Plugin features?

  • Automatic Image Optimization.
  • Parallelize HTTP connections.
  • Page speed improvement.
  • Auto-Path find (Automatically find server root path, sub-domain path, plugin resources path…).
  • Cache loss minimization.
  • Sub-domain real-time health tracking.
  • Auto recovery from resource files bad sync.
  • Ability to activate / deactivate sub-domains
  • Plugin Updates aware. (automatically re-sync files and database after an update)

Requirements?

The plugin is programmed to be aware of this requirements, and if not fulfilled it will not change anything on your Blog.
It will not break your Blog code!

  • Your server needs to have a working GD Library module for PHP.
  • You should have a PHP installation with a minimum version of 5.1.3
  • Access to your server Administration Painel (cPanel, DirectAdmin, Plesk) in order to create new sub-domains for your domain.

Additional help

You can find additional information about adding new sub-domains to your server administration system (cPanel, DirectAdmin, Plesk) by visiting this plugin homepage: http://www.joseairosa.com/2010/05/17/wordpress-plugin-parallel-loading-system/

What’s in the cooking pan?

This was only the first release of the plugin. I’ve got a lot of new ideas that I would like to see implemented on next releases.
Some of them are:

  • Also parallelize CSS and JavaScript loading.
  • Add support to also load external images. At the moment it will only load locally stored images. (DONE)
  • Add real-time rewrite functions to CSS and JavaScript. That way, images that have been called from the CSS file will also be parallelized.
  • Overall improve of the code. (DONE & Ongoing)
  • Add options to manage image quality rendering.
  • Bug fixes (when found or reported).
  • And much more…

If you have any features that you would like to see implemented, please don’t hesitate to tweet me (http://twitter.com/joseairosa) or mail me (me@joseairosa.com) 🙂

Thank you!

I would like to give a big thank you to Marco Sousa (http://twitter.com/h1brd) from Scarletbits.com (http://scarletbits.com) and Filipe Oliveira (http://twitter.com/bluekora) for the help and support given! Without them this would not be possible.

Installation

  1. First you need to download it from WordPress Plugin Repository.
  2. Upload the contents of the compacted file to your plugin folder on your WordPress installation.
  3. Go to your WordPress Administration page and activate the Plugin (Plugins → Installed → WP-PLS → Activate)
  4. Go to Settings → Parallel Loading System

Changelog

Version bug fix.

0.1.9.1

  • Fixed a bug where the version of the plugin was not updated at the plugin page

0.1.9

  • Added support for timthumb.php and other thumbnail generators (Thank you all that sent feedback)

0.1.8

  • Changed the way the plugin detects what OS you’re on. (Thank you Christian)
  • Changed the way the plugin detects folder separators. (Thank you Christian)
  • Added support for when your blog is itself installed on a subdomain
  • Added information on adding index.php to your subdomains

0.1.7.1

  • You can now change the root path at any time.
  • Bug fixes.

0.1.7

  • Few changes to better adapt to version 3.0 of WordPress

0.1.6.2

  • Bug fixes. (Thank you Joe for the help)

Full changelog on WordPress.org →

Screenshots

Overall view of the active and inactive sub-domain management.
Overall view of the active and inactive sub-domain management.
Adding new sub-domain form.
Adding new sub-domain form.
Results of before and after application of this plugin.
Results of before and after application of this plugin.
Results of before and after when viewed under FireBug Page Speed Performance Analizer.
Results of before and after when viewed under FireBug Page Speed Performance Analizer.

For developers

Is this your plugin? Show off the numbers.

Add a live badge to your site, docs or GitHub README. It updates on its own — no account needed.

Active installs badge Rating badge Health score badge

Best WP Parallel Loading System alternatives

All image optimization plugins →
Alternatives
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2 Smush – Image Optimization, Compression, Lazy Load, WebP & CDN Smush Compress and optimize images, enable lazy load, serve WebP & AVIF, and speed up your site… by WPMU DEV 1M+ ★★★★★★★★★★ 4.8 (6.1K) 2 weeks ago 97
3 Imagify Image Optimization: Optimize Images | Compress & Convert to WebP/AVIF Imagify Image Optimization: Optimize Images Image optimization in 1‑click: compress, resize & convert to WebP/AVIF – free up to… by WP Media 1M+ ★★★★★★★★★★ 4.3 (1.7K) 3 weeks ago 95
4 Converter for Media – Optimize images | Convert WebP & AVIF Converter for Media – Optimize images | Convert WebP & AVIF Speed up your website by using our WebP & AVIF Converter. Optimize images and serve WebP… by Mateusz Gbiorczyk 500K+ ★★★★★★★★★★ 4.9 (1.1K) 1 month ago 93
5 ShortPixel Image Optimizer – Optimize Images, Convert WebP & AVIF ShortPixel Image Optimizer Optimize images & PDFs smartly. Create and compress next-gen WebP and AVIF formats. Smart… by ShortPixel 300K+ ★★★★★★★★★★ 4.5 (819) 3 weeks ago 95
6 Optimole – Optimize Images | Convert WebP & AVIF | CDN & Lazy Load | Image Optimization Optimole Automatically optimize images with bulk compression, lazy loading, WebP/AVIF conversion &… by Optimole 200K+ ★★★★★★★★★★ 4.7 (640) 5 hours ago 95
7 reSmush.it : The original free image compressor and optimizer plugin reSmush.it reSmush.it is the FREE image compressor and optimizer plugin - use it to optimize your… by ShortPixel 100K+ ★★★★★★★★★★ 4.3 (165) 1 month ago 89
8 Robin Image Optimizer – Unlimited Image Optimization, WebP & AVIF Robin Image Optimizer Unlimited automatic image optimization for WordPress. Compress images, convert to WebP, and… by Themeisle 100K+ ★★★★★★★★★★ 4.4 (131) 1 week ago 93
9 QODE Optimizer QODE Optimizer The QODE Optimizer plugin is developed to allow you to convert, compress and adjust file… by Qode 30K+ ★★★★★★★★★★ No reviews 5 days ago 74
10 ThumbPress – Compress Images, Manage Thumbnails, Detect Image Issues, WebP/AVIF, Lazy Loading, Hotlinking & More ThumbPress All-in-one WordPress image optimization: disable thumbnails, compress, convert to WebP &… by Codexpert, Inc 20K+ ★★★★★★★★★★ 3.6 (110) 2 hours ago 78

FAQ

WP Parallel Loading System: quick answers

Straight answers, pulled from live WordPress.org data.

Live data from WordPress.org · checked Sep 29, 2026

Is WP Parallel Loading System free?

Yes. WP Parallel Loading System is free to download and use from the official WordPress.org plugin directory.

Is WP Parallel Loading System safe to use in 2026?

WP Parallel Loading System shows warning signs in 2026 — compare the alternatives below before installing. It runs on 20+ sites, is rated 2.7/5 and was last updated 16 years ago, and scores 24/100 on our health check.

How many websites use WP Parallel Loading System?

WP Parallel Loading System is active on 20+ WordPress websites and has been downloaded 20,563 times since it launched in May 2010. It was downloaded 48 times in the last 30 days.

Does WP Parallel Loading System work with WordPress 7.1?

WP Parallel Loading System is officially tested up to WordPress 3.0.5, while the latest release is 7.1.2. It may still work, but try it on a staging site first.

When was WP Parallel Loading System last updated?

The latest version, 0.1.9.1, was released on February 2, 2011 (16 years ago).

What are the best alternatives to WP Parallel Loading System?

The most popular alternatives to WP Parallel Loading System are Image Optimizer (1M+ installs), Smush (1M+ installs) and Imagify Image Optimization:… (1M+ installs).

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