Raise a WordPress site's PageSpeed score with GitHub Copilot in VS Code

Raising a WordPress PageSpeed score with GitHub Copilot in VS Code means asking its chat to preview and then apply an xSpeed optimization pass through xSpeed Hub, confirming each tool call.

list_sitesget_score_historylist_modulesoptimize_sitegenerate_critical_csspurge_cacherun_speed_test

Last updated: October 2026

Example session · GitHub Copilot in VS Code

You: The portfolio site scores badly on mobile. See what xSpeed Hub can do, safe level only.

list_sites read-only
→ 3 sites; portfolio is portfolio.example.com

optimize_site(site: portfolio, aggressiveness: safe, dry_run: true) dry run
→ plan: 3 settings to apply (lazy-load images, compression, browser cache), nothing changed

GitHub Copilot in VS Code: At the safe level it would turn on lazy-loading, compression and browser caching. Nothing has changed yet. Apply these three to portfolio?

You: Yes.

optimize_site(site: portfolio, aggressiveness: safe) changes site
→ applied 3, undone 0, unfixable: 1 video background, large gallery images

GitHub Copilot in VS Code: All three settings are on. The video background and the gallery images are on the unfixable list, so the score may stay below what you want until those change. Open the home page and the gallery in a browser and check the console.

How GitHub Copilot in VS Code handles this

You are in VS Code, probably with the theme or a plugin repository open, and you open Copilot chat and ask for a faster site. Copilot lists your sites, then calls optimize_site with dry_run on. At the default Manual permissions level, VS Code shows a confirmation dialog for any tool call that is not auto-approved. Confirm it, and you get the plan back in the chat: which settings xSpeed would turn on at the standard level, with nothing changed on the site.

Read the plan against what you know of the theme, then ask Copilot to apply it. The real pass applies each setting one at a time, checks the page after each, and undoes anything that breaks it. Give it up to two minutes per site. The answer lists what was applied, what was undone and why, and what is unfixable, so a score that stays lower than you hoped has a stated reason rather than a vague one. A site that is already tuned says everything is already on, and that is a complete result.

Copilot can also use your editor context to help with the leftovers. The unfixable list names what caching cannot reach, and those are things you can fix in the project open beside the chat. When the pass is done, the Hub gives Copilot a list of verify_urls and tells it to look at the pages before it says the pass worked. The plugin cannot run your JavaScript, so open those pages in a browser with the console visible and report anything odd back into the chat.

Set up GitHub Copilot in VS Code once

Already connected? Skip to the prompts. Alternatives and troubleshooting are on the GitHub Copilot in VS Code guide.

1Put your sites in xSpeed Hub

Sign in at app.xspeedcache.com with Google or email; the Hub is free and has no site cap. Then connect each WordPress site from its own dashboard: click Connect Hub in the xSpeed Cache top bar, then Connect via xSpeed Hub. Each site needs the free xSpeed Cache plugin.

2Add xSpeed Hub to your user mcp.json

Open the Command Palette and run MCP: Open User Configuration, then add this entry. Servers in your user profile are available in every workspace. MCP: Add Server walks you through the same thing, and the project-level .mcp.json file works too if you want the entry shared with your team; that file uses a top-level mcpServers object instead of servers.

mcp.json (MCP: Open User Configuration)

{
  "servers": {
    "xspeedhub": {
      "type": "http",
      "url": "https://app.xspeedcache.com/xspeed/mcp"
    }
  }
}

3Start the server and sign in

Run MCP: List Servers, pick xspeedhub and choose Start. VS Code asks whether you trust the server, then opens a browser page where you sign in to xSpeed Hub and approve access. There is no token to paste, and VS Code keeps the credentials it receives. Open the Chat view and use the Configure Tools button to see the xSpeed tools.

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MCP: List Servers

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Full GitHub Copilot in VS Code setup, sign-in options and FAQ

Before you send a prompt that changes something

Reads change nothing on your sites, though contact_support emails xSpeed support. Writes run once your connection allows them, so your client's approval prompt and a read-only connection (the token's Read-only everywhere switch, or a Viewer sign-in) are the gates that matter. In VS Code the default permission level is Manual permissions: a tool call that is not auto-approved shows a confirmation, and you can allow it once or for the session, the workspace or all future calls. Chat: Manage Tool Approval lists tools grouped by MCP server, so you can trust get_cache_status and the other reads while purge_cache and update_settings stay on a prompt. Allow all, Autopilot and global auto-approval skip those prompts, including for external tool calls, and then a write runs as soon as your connection allows writes. xSpeed Hub has no confirmation step of its own.

What do I ask?

Three prompts written for GitHub Copilot in VS Code. More for this job are below.

Prompt for GitHub Copilot in VS Code

Ask xSpeed Hub for a preview of the optimization on the portfolio site at the safe level, and show me the plan before anything is applied.

Prompt for GitHub Copilot in VS Code

Using xSpeed Hub, apply that plan to portfolio, then list the pages I should check and what an error would look like.

Prompt for GitHub Copilot in VS Code

Which items on the xSpeed Hub unfixable list can be fixed in the files open in this workspace?

What happens, step by step

optimize_site is the Hub tool for "make my site faster". It measures the site, applies the recommended xSpeed settings one at a time, checks the page still renders after each change, undoes anything that breaks it, and reports what it applied, what it undid and what it could not fix. It reaches caching and asset delivery only. Page weight, images hosted on another domain and heavy video are outside it, and the report says so instead of claiming a win.

See where the site stands

The agent reads get_score_history for the last stored scores and list_modules for which modules exist on that site and what state they are in. Neither changes anything.

Preview with dry_run

optimize_site with dry_run: true returns the plan: each change and its tier, what would be skipped (already on, or needing a higher aggressiveness) and what it cannot fix. Nothing is applied. The tool description tells the agent to prefer this before the first real run on a site you have not optimized before.

Apply it

optimize_site without dry_run applies the plan. aggressiveness is safe (removals and server-side changes only), standard (the default) or aggressive, which includes settings known to break some themes and should be opted into deliberately. A run can take up to about 2 minutes per site.

Look at the site afterwards

When changes were applied, the result carries verify_urls and a note. The site checks its own HTML and reverts anything that breaks it, but it cannot run JavaScript, so verified: true does not prove the page works in a browser. The Hub tells the agent to open those URLs and check the page renders and the console is clean, or to tell you which URLs to check.

Reach for a number only if you named one

target_score (1 to 100, Pro sites only) turns one pass into repeated rounds toward that score, up to max_rounds, with 3 as the most per site. Each round is a real PageSpeed measurement and up to about 2 minutes. The result says why it stopped, and diminishing returns means what is left is outside what caching can reach.

Critical CSS on Pro sites

generate_critical_css generates above-the-fold CSS so the first screen can paint without waiting for the full stylesheets. It needs the Pro Critical CSS module on that site, and the site answers with an unknown-tool error without it. Pages are rebuilt with it on their next build, so the agent purges the cache afterwards.

Reference

Main tool	optimize_site (write): measure, apply one setting at a time, verify, undo what breaks, re-measure
Preview	dry_run: true returns the plan and changes nothing
aggressiveness	safe, standard (default) or aggressive
Every site at once	site: "all" or a list of handles, one result per site, sites run one after another; the Hub's confirm-once instruction does not name optimize_site, so your client's prompt is the gate
Time	Up to about 2 minutes per site
target_score	1 to 100; needs Pro on the site; without it the site runs one pass and says so
max_rounds	Up to 3 per site; only sent along with target_score; 12 rounds in total per call
Wide fan-out with a target	Each site gets fewer rounds, and the result carries a note saying so
Result fields	applied, skipped, reverted, unfixable, score, verified, rounds; verify_urls after a run that changed something
Already tuned site	Returns "everything is already on" plus what it cannot fix; that is an answer, not a failure
Critical CSS	generate_critical_css (write), Pro Critical CSS module required; purge_cache afterwards
Read-only connection	optimize_site and generate_critical_css are refused; dry_run is still a write call, so it is refused too. Applies to the connection token with Read-only everywhere on and to a Viewer sign-in, not to other OAuth sign-ins

Rules worth keeping

Run dry_run first. optimize_site changes live site settings as soon as your connection allows writes. The tool description tells the agent to preview first on a site that has not been optimized, but that is guidance, so your client's approval prompt and a read-only connection (the connection token with Read-only everywhere on, or a Viewer sign-in) are the real gates.
Keep aggressive for a deliberate choice. It includes settings known to break some themes, and the agent should say so before using it.
After a run that changed something, open the pages in verify_urls. The HTML checks cannot run JavaScript, so a page can pass them and still be broken in a browser. Do not call a run safe because verified is true.
Relay the unfixable list. When a site is already tuned, the honest answer is that caching is done and the rest is page weight, hotlinked images or DOM size. The agent should not retry the tool or claim a gain it did not make.
Only ask for target_score when you want the site driven to a number. Each round costs a real PageSpeed measurement, and a plain "make it faster" is one pass.

Good to know with GitHub Copilot in VS Code

The VS Code confirmation dialog can allow a tool once, or for the session, the workspace or all future calls, and a broader choice outlives the one call. If you accept it for optimize_site while previewing, the real pass follows with no dialog at all, because the dry run and the real pass are the same tool. Allow it once, and use Chat: Manage Tool Approval to trust the reads while optimize_site stays on a prompt. Allow all, Autopilot and global auto-approval skip the dialog for every tool. A chat request can enable at most 128 tools, and the Hub adds 29 to the pool.

More prompts for this job

They work in any client connected to xSpeed Hub.

Prompt

Ask xSpeed Hub to preview what optimize_site would change on shop with a safe pass. Do not apply anything.

Prompt

Use xSpeed Hub to optimize the blog site with the standard pass, then give me the pages to check by hand.

Prompt

With xSpeed Hub, get docs to a mobile PageSpeed score of 90 if you can, and tell me why it stopped if it does not get there.

Prompt

Use xSpeed Hub to show me what optimize_site would do on every site, as a dry run, and list which sites have the most left to change.

Prompt

Use xSpeed Hub to generate critical CSS for shop, then purge the cache so the pages are rebuilt with it.

Prompt

With xSpeed Hub, optimize shop, then compare the new PageSpeed score with the last stored one.

Prompt

Using xSpeed Hub, what could optimize_site not fix on the shop site?

Frequently asked questions

By default, yes. VS Code starts in Manual permissions and shows a confirmation for tool calls that are not auto-approved, and you can allow a tool once, for the session, for the workspace or for all future calls. If you allow it broadly, or choose Allow all or Autopilot, later calls run without a dialog, and the Hub runs the pass as soon as your connection allows writes.

The Hub exposes 29 tools. A chat request can enable at most 128 tools across all sources, so xSpeed fits, but a crowded setup may need some servers or tools switched off in the tools picker.

It measures the site, applies the recommended xSpeed settings one at a time, checks that the page still renders after each change, and undoes any change that breaks it. It then reports what was applied, skipped and reverted, and what it could not fix. It reaches caching and asset delivery only.

Yes, especially on a site you have not optimized before. dry_run: true returns the plan, what would be skipped and what cannot be fixed, and changes nothing. The tool description tells the agent to prefer it, but nothing forces it, so say so in your prompt if you want a preview.

Yes, with target_score, on a site that has xSpeed Pro. It repeats measure, apply and re-measure for up to 3 rounds per site and stops early when rounds stop helping, saying why. On a Free site the score target is ignored and you get a single pass with a note that no iterative tuner is installed.

That is a real answer. The settings it can apply were already enabled, so there was nothing to change. The result also lists what it could not fix, such as page weight, images hosted on another domain or DOM size, and those need changes outside a caching plugin.

The site checks its own HTML after each change and reverts anything that breaks it, but it cannot run JavaScript. After a run that changed something, the Hub tells the agent to open the returned verify_urls and check the page renders and the console is clean, or to give you the URLs to check yourself.

No. It needs the Pro Critical CSS module on that site, and without it the site answers with an unknown-tool error. On a Pro site, purge the cache afterwards, because pages already cached were built without the critical CSS.

Keep going

Raise the PageSpeed score with other agents

More with GitHub Copilot in VS Code

Purge the cache Find out why pages are not cached Scan a site's speed Track PageSpeed scores Tune cache settings Warm the cache Set up Redis object cache Manage Cloudflare Manage every site at once

Documentation

From the blog

Raise the PageSpeed score, from GitHub Copilot in VS Code.

xSpeed Hub is free and has no site cap. Connect your sites once and ask from the agent you already use.

Open xSpeed Hub GitHub Copilot in VS Code setup