How to check if your inn's WordPress is slow or slow | Isolate the cause using AI

When I open the inn’s homepage on my smartphone, the photos are difficult to display. You will have to wait until you can press the reservation button. Even the management screen is heavy.

In such a case, adding a cache plugin or deleting images all at once may cause display problems and increase problems with the reservation function. There are multiple causes for slowdowns, including images, themes, plugins, servers, externally reserved parts, and access concentration.

In this article, the host, who is not an IT expert, explains how to isolate the cause before making changes, using Codex and Claude Code to help investigate.

Conclusion: Recreate the slow locations and then examine them one by one

Proceed in the following order.

Record which pages are slow on which devices and lines
Check if customer reservations and inquiries are affected.
Save the speed and screen before changes
Divide the possible causes into page content, external parts, WordPress, and server.
Change just one thing in the verification environment
Re-check not only speed but also display, reservations, and inquiries.

Just saying “the whole site is slow” is not enough to find the cause. Determine if it only has the top page, only articles with a lot of photos, only the reservation page, or whether the admin screen is also slow.

Record slowness first

Record the following items without including any personal information.

Check items	Record example
Target URL	Top, guest room, access, reservation information
Date and time of occurrence	Weekday mornings, weekend nights, etc.
Device	iPhone, Android, PC
Line	Wi-Fi, mobile line
Symptoms	White screen, waiting for photos, buttons not responding
Frequency	Every time, sometimes, only at a specific time
Management screen	Fast/Slow/unconfirmed
Last minute changes	Image additions, updates, plugin changes, etc.

Check not only the inn’s Wi-Fi, but also your smartphone’s mobile network. To avoid the effects of caches and extensions left only on staff terminals, it may be helpful to use a different browser or an incognito window.

Check the impact on your reservation first

Priority for speed improvements is determined by the impact on guests, not by scores.

Examples of high priority:

The top page does not open and you cannot check the business status of the inn.
The reservation button is not displayed or cannot be pressed.
Failed to navigate to external reservation page
Unable to submit inquiry form
Phone number and access information are not displayed
Screen freezes on smartphone

Even during the investigation, we will provide easy-to-understand guidance on alternative reservation routes such as telephone and OTA.

Don’t judge based only on PageSpeed Insights scores

Google’s PageSpeed Insights inspects pages on smartphones and PCs and suggests improvements. However, there are differences in the data displayed.

Real user data

Data compiled from past experiences of Chrome users. For small sites or new pages that don’t have a certain amount of data, individual page data may not be displayed. This is a trend for the past 28 days, so today’s changes will not be reflected immediately.

Test environment data

This is the result of Lighthouse reproducing certain conditions and inspecting the page at that time. Although it is useful for investigating the cause, it does not represent the actual experience of all customers. Results may vary depending on the measurement location and communication conditions.

Don’t delete the plugin just because your score has dropped just once; check it multiple times with the same URL and conditions and compare before and after the change.

Read Core Web Vitals for lodging

The current major Core Web Vitals are LCP, INP, and CLS.

LCP: Speed until main photos and headlines are visible
INP: From when you operate a button etc. until the screen responds
CLS: Degree to which photos and buttons shift during loading

On accommodation sites, this can be linked to symptoms such as large guest room photos being displayed with a delay, the reservation button being moved later, and external parts interfering with operation. Check which elements were targeted, not just terms and numbers.

Divide the causes into six

1. Photos and videos

On accommodation sites, photos of guest rooms, food, and cats tend to take up much of the page space.

Items to check:

Are you using images that are significantly larger than the display size?
Are you posting photos in PNG that do not require PNG?
Can you use a suitable format such as WebP?
Are you loading the same photo over and over again?
Is it possible to lazily load off-screen images?
Is the video loading automatically when the page is displayed?

Before deleting the original image, back it up and check the effect on image quality, smartphone display, and images for sharing on SNS.Try batch conversion in a verification environment.

2. Theme and screen parts

Sliders, animations, web fonts, large background images, reservation pop-ups, etc. can slow loading and operation.

Rather than removing all design, look at what is taking up your time on the target page. Rather than directly editing the theme file, priority is given to child themes, official settings, and the scope of maintenance by the production company.

3. Plugin

You cannot judge the weight just by the number of plugins. Sometimes a single plugin is heavy, and sometimes multiple functions overlap the same process.

Instead of stopping all at once during production, compare them one by one in the verification environment. Plugins for reservations, inquiries, SEO, cache, image optimization, and security will be greatly affected by suspension, so we will first check how to restore them.

4. Cache

Caching is a mechanism to efficiently serve the same page, but it may exist in multiple locations: WordPress, server, CDN, and browser.

If you use multiple cache plugins, problems may occur such as old screens remaining, only the management screen being different, or reserved parts not working. Examine the current administrative location and then change it.

5. Server and database

If the top page or management screen is slow, if it suddenly slows down depending on the time of day, or if errors increase, then server resources, PHP, databases, storage, access concentration, etc. are also possible problems.

For VPS, our technical staff will check the CPU, memory, disk, PHP and database logs. On the rental server, check the resource limits, failure information, and support range of the contract plan in the official information. Reboot before taking measurements to avoid erasing evidence.

6. External services

Reservation widgets, maps, SNS embedding, videos, chats, access analysis, advertisements, etc. use external communications. Even if WordPress itself is fast, pages may slow down while waiting for responses from external services.

Before completely removing an external component, determine whether it can be replaced with a regular link, can be loaded after a click, or is a necessary feature for reservations.

Distinguish the “cause of slowness” and “improvement ideas”

Even when the AI reads the PageSpeed results, it does not immediately execute the suggestions.

Observed fact: Large images are the main display element
Possible causes: image size, delivery format, server response, etc.
Additional confirmation: Original image size, presence of cache, comparison with another page
Improvement idea: Try compression by duplicating the image
Implementation location: Verification environment
How to restore: Return to original image and settings
Check items: Image quality, smartphone display, reservation button, speed

This format reduces guesswork.

Safe Improvement Procedures

Check backup and restore methods
Narrow down the improvement target to one page or one element
Save the screen and speed before changes
Change just one thing in the verification environment
Re-measure under the same conditions
Check the display on your PC/smartphone
Check reservations, inquiries, maps, and videos
Record effects and side effects
People approve the production update

If the improvement is small but the maintenance burden increases significantly, you can decide not to adopt it.

Things that can be left to AI

Organizing slow URLs and reproduction conditions
Compare and summarize PageSpeed results
Image size and external request candidate extraction
Candidate cause classification for themes, plugins, and servers
Comparison of HTTP, screen, and speed before and after the change
Documentation of verification steps and reverts
Monthly report creation

Don’t leave it to AI:

Bulk suspension/deletion of production plugins
Batch deletion of images and databases
Unfounded server restart
Complete cache changes including reservation functionality
Database optimization with backup unconfirmed
Removal of necessary functions based only on score

Request text to AI that can be used with copy and paste

First, investigate without making any changes.

The inn's WordPress site feels slow.
Do not change plugins, themes, images, caches, or servers yet.

Please ask me about the slow URL, device, line, time zone, and symptoms.
The confirmed facts include page content, images, external services, WordPress,
Please sort out possible causes and additional checks by dividing the issue into servers.

Please do not output reservation information, authentication information, or private logs.

Compare PageSpeed results

Compare PageSpeed Insights results for the same URL.
Separate actual user data and test environment data, do not judge based on scores alone,
Please explain the covered elements of LCP, INP, and CLS and their impact on accommodation reservations.

Organize the proposed changes in the order of expected effects, risks, amount of work, and how to revert.
Please do not reflect it on the site yet.

Verify one improvement

Please reflect only one approved speed improvement to the verification environment.
Please show the backup before the change, target files/settings, and how to restore.

After the change, measure the speed under the same conditions, and check the display on your PC/smartphone,
Check the impact on reservations, inquiries, maps, and videos.
Please do not change the production environment.

Checklist for the host

[ ] Recorded slow URLs, devices, lines, and time zones.
[ ] We have confirmed the impact on reservations and inquiries first.
[ ] Saved the screen and speed before the change
[ ] Differentiated between real users of PageSpeed and testing environment.
[ ] Separate images, themes, plugins, and cache
[ ] Also included servers and external services.
[ ] Plugins are not stopped all at once during production.
[ ] I confirmed how to back up and restore.
[ ] Only one change was made in the verification environment
[ ] Comparing before and after changes under the same conditions
[ ] Confirmed display on PC/smartphone
[ ] Reconfirmed reservations, inquiries, maps, and videos.
[ ] Recorded improvement effects and side effects

If photos are the main cause, please proceed to How to safely lighten photos on your accommodation site.If the site does not open, prioritize first 30 minutes after WordPress failure over speed improvement. The causes of themes and plug-ins are explained in How to isolate the cause of display collapse from AI, and continuous monitoring is explained in How to monitor your inn’s WordPress from the outside.

Information used for reference

Summary

When WordPress is slow, don’t increase the speed plugin first, record the slow pages, devices, lines, and times. We separate possible causes into images, themes, plugins, caches, servers, and external services and compare them one by one in a verification environment.

AI is suitable for organizing measurement results and candidates, but it does not automatically stop, delete, restart, or change production in bulk. Make improvements based not only on speed, but also on ensuring that guests can safely complete their reservations and inquiries.