This thread is resolved. Here is a description of the problem and solution.
Problem: The client reported significant slowdowns on their website when WPML was enabled, despite having a high-performance server setup. The site performed well without WPML and with fewer active plugins, but slowed down considerably when more plugins were activated alongside WPML.
Solution: We conducted a series of tests to isolate the issue, including updating themes, minimal plugin activation, and detailed performance monitoring. It was determined that the performance issue was not caused by WPML itself but by a third-party plugin, specifically 'Ultimate GDPR & CCPA'. This plugin was found to consume a significant amount of runtime due to a function running a regex callback on numerous posts, which severely impacted site performance. We recommended deactivating this plugin or contacting its support for a resolution.
If this solution does not resolve your issue, or if it seems outdated or irrelevant to your case, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If problems persist, please open a new support ticket at WPML support forum for further assistance.
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Background of the issue:
I am trying to assess the impact of WPML on my site's performance. I have a very good server setup with 24 cores, 96GB RAM, and NVME SSD. I created a staging site to compare the performance with WPML enabled and disabled. All plugins are the same, except for the AAA optimizer on the production site. The staging site without WPML and without any caching loads much faster than the production site with WPML enabled, even though the production site uses LiteSpeed Cache and Redis. Here is a video recording, as video is too big to upload: hidden link. I expected WPML to load with an acceptable speed.
Symptoms:
Pages load very slowly when WPML is enabled, despite having a high-performance server and caching mechanisms in place.
Questions:
Why does WPML slow down my site significantly?
How can I improve the performance of my site with WPML enabled?
AI cut out, that the AAA optimizer plugin is not the problem. I just installed it afterwards as I thought maybe some autload scripts slow down the site. The problem is WPML. Site works fast without WPML.
just for your info. I now disabled WPML for the live site, too to test how litespeed cache is working without it and the site has crazy speed now and the cache is hitting too. Before cache very often missed with WPML on.
I really hope you can help me with this. I really want to use WPML, it is really important plugin for me.
Languages: English (English )German (Deutsch )French (Français )
Timezone: Europe/Zagreb (GMT+02:00)
Hi,
To better understand where WPML might be causing the slowdown, could you please provide the following performance metrics (if available)?
* Server response time before and after activating WPML
* Total page generation time, including TTFB (Time to First Byte), PHP execution time, etc.
* Database performance:
* Number of queries executed with and without WPML
* Any particularly slow or heavy queries identified (e.g., via Query Monitor, New Relic, or similar tools)
* Server resource usage (CPU, memory) during page loads, both with and without WPML
* Whether you noticed higher cache miss rates with WPML and if possible, what kind of pages were affected (e.g., multilingual, archive, custom post types)
If there’s anything else you’ve already measured or observed — such as object cache hit/miss ratios, differences in HTML output, or plugin conflicts — that would also be very helpful.
Once we have more insight into the metrics, we can work on identifying what specifically in WPML is impacting performance and look into possible optimization steps.
Server Times meassured from Germany: DNS 10ms, Connect 7ms, TLS 19ms, TTFB 41ms
pingdom(Germany): Load Time 3.39s , 113 requests, page size 6.2MB
Query Monitor:
Home Page 1.52s, 67.3Mb 0.11s 314Q
About Us: 1.41s 73.4MB 0.11s 325Q
Nothing in php slow logs
No Litespeed Cache, WPML ON, No CDN:
Server Times meassured from Germany: DNS 8ms Connect 30ms TLS 42ms TTFB 110ms
Pingdom (Germany): Load Time -0.00s (wtf?), 3305 requests, page size 79.6MB . Makes no sense.
Query Monitor:
Home Page 1.74s 80.0MB 0.11s 430Q
About Us: 1.70s 80.7MB 0.11s 448Q
Nothing in php slow logs
There are some serverside caches which I can't disable which may result in meassured fast loading speeds when WPML is on, but the user experience is slow with WPML on. Nevertheless, the sites becomes slow when WPML is enabled. As shown in the video.
Hello,
My name is Carlos, and I will continue working on this ticket
Thank you very much for sharing the video and the information requested by my colleague Bruno.
I kindly ask you to share the access credentials to the staging site so I can reproduce the issue and run some troubleshooting steps. Your next message will be private, so you can securely share the access credentials to the staging site.
I have updated an outdated theme, then ran some troubleshooting steps and left the site in a minimal installation (only WPML plugins, Woocommerce, and Woocommerce Multilingual & Multicurrency activated), and the performance issue has disappeared.
I kindly ask you to start activating the rest of the plugins, one by one, until the issue appears and you find the culprit.
The used theme which is Divi theme was at the latest version.
I already tested the performance with every single plugin. WPML slows down as soon as more plugins are activated and more strings have to be translated. I can't find a single culprit. That's the problem.
I sadly can't tell, because it doesn't matter if I switch off plugins one by one. Let's say I have 20 active plugins and when having 30 active plugins the problems start, depending on which plugins are active. When having all 40 plugins activated and I deactivate just 1 plugin, the performance is bad even if I go through all 40 options with 1 plugin deactivated. I can't find any culprit. So every plugin was deactivated once and I still run into the performance problems.
I left only the theme and the WPML plugins active, and the issue wasn't happening, which means that the cause of the performance problem is not the WPML plugins or the theme.
I recommend that you activate the WordPress debug mode (https://developer.wordpress.org/advanced-administration/debug/debug-wordpress/) and contact your hosting providers to start activating the rest of the plugins, one by one, until you find which one is causing the performance issue, or if there is a problem on the server side or in the database.
I tried with the troubleshooting plugin many times to dertemine the culprit but it's really not possible. It has to be a combination of plugins which cause this slow down. It's impossible to find the culprit for me.
I even disabled the serversided cache now to make sure that there is no overlapping when disabling plugins. Still not able to determine the problematic plugin if it is just one.
