Scan a website for speed problems with GitHub Copilot in VS Code

Scanning a site's speed with GitHub Copilot in VS Code means asking its agent mode to run an xSpeed Scan and return the graded report inside the chat panel next to your project.

list_sitesget_speed_scanrun_speed_scan

Last updated: October 2026

Example session · GitHub Copilot in VS Code

You: Did the image-loading change in this PR help? Use xSpeed Hub to scan shop and compare.

get_speed_scan(site: shop) read-only
→ Latest scan before the PR: desktop grade B, mobile grade D

run_speed_scan(site: shop, fresh: true) uses quota
→ Desktop grade B, mobile grade C. Image check passes; top failing check: server response. Report link included.

GitHub Copilot in VS Code: Mobile moved up one grade and desktop held. The image check passes, and server response is the top failing check. I have drafted a comment for the PR with the report link.

How GitHub Copilot in VS Code handles this

You are reviewing a pull request for a WordPress site and the question comes up: did this make the page slower? In Copilot agent mode you ask it to scan the site with xSpeed. It calls run_speed_scan through the Hub server, which takes a site handle, and gets back a grade out of 100 with the desktop run as the headline and the mobile run alongside. The failing checks come with their evidence, so you can quote them in the review.

Copilot is a good fit for a fix that spans files. It reads the ranked failing checks, finds the matching code in your workspace, and proposes the changes, and you accept them in the usual diff view. Then you ask for a fresh scan, and it compares the new report with the history it read earlier with get_speed_scan, which spends nothing.

The no-account Scan MCP covers the case where the site is not yours or not in your Hub: paste a public URL and it grades it, read-only, with four scans per caller per ten minutes. The two servers together add 34 tools, which matters because a chat request can enable at most 128 tools, so clear the servers you are not using in the tools picker.

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

4Add the xSpeed Scan MCP for sites you do not run

Prompts that scan a public URL use the xSpeed Scan MCP, a separate server from the Hub. Add it to GitHub Copilot in VS Code the same way as the Hub above, as a second server (xspeedscan, for example) with the URL https://xspeedcache.com/scan/mcp, and leave out any sign-in setting, such as an OAuth or auth option or an Authorization header, because the Scan MCP needs no account, token or sign-in. On a plan that allows one custom connector, add whichever server the prompts you use need.

Text

https://xspeedcache.com/scan/mcp

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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

Use xSpeed Hub to scan the production site and summarize the grade and the top three failing checks for my PR comment.

Prompt for GitHub Copilot in VS Code

With xSpeed Hub, compare the latest scan for shop with the one before it and tell me whether this change helped.

Prompt for GitHub Copilot in VS Code

Use the xSpeed Scan MCP to scan this competitor URL and list their weakest dimension.

What happens, step by step

An xSpeed Scan grades a site from 0 to 100 using server probes (time to first byte, compression, cache evidence, redirects, platform detection) plus a Lighthouse run, and names the fix for every failing check. An agent can start one two ways. Through xSpeed Hub, run_speed_scan scans a site you have connected. Through the no-account Scan MCP at https://xspeedcache.com/scan/mcp, it scans any public URL and cannot change anything. Either way you get a report link to share.

Check what the site already scored

get_speed_scan without a scan id returns the site's scan history, newest first, plus a summary of the latest report. It starts nothing and spends nothing, so the Hub tells the agent to read it first when you ask what a site scored.

Start a scan

run_speed_scan runs the full scan on a site you connected to the Hub. strategy is both (the default), desktop or mobile; one device alone costs half the engine's quota. The scan takes 20 to 60 seconds. The Hub waits about 50 seconds and, if the scan is still running, hands back a scan id.

Poll if it is still running

Call get_speed_scan with scan_id. While the scan runs it returns the running status and a note to ask again in about 20 seconds. The report page is live from the start and refreshes itself.

Read the result

The summary carries the grade, the four dimension scores, what was measured and the top fixes ranked by points recoverable, each with the xSpeed feature that fixes it. The headline grade is the desktop run. The mobile run is graded alongside it, so the agent should mention both when they differ.

Scan a site you do not run

For any other public URL, the agent uses the Scan MCP at https://xspeedcache.com/scan/mcp. There is no account and no sign-in. It takes a url, returns the same graded report and a link at xspeedcache.com/scan/r/<id>, and is limited to 4 scans per caller per 10 minutes.

Fix, wait, re-scan

After a change, wait several minutes and scan again with fresh: true. Without it, the scan service reuses any report from the last 10 minutes and the agent will show you the old number.

Reference

Hub route	run_speed_scan, then get_speed_scan with scan_id; only for sites connected to your Hub
Scan MCP route	https://xspeedcache.com/scan/mcp, no account, 5 tools, read-only, any public URL
Scan MCP limit	4 scans per caller per 10 minutes
Why run_speed_scan is a write	It spends a shared scan allowance and stores a report; it changes nothing on the site
Read-only Hub connection	run_speed_scan is refused; get_speed_scan still works. Applies to the connection token with Read-only everywhere on and to a Viewer sign-in; an OAuth sign-in gets the scopes the client asks for
Duration	20 to 60 seconds; the Hub waits about 50 seconds, then returns a scan id
Poll argument	scan_id on the Hub tool, scanId on the Scan MCP tool
strategy	both (default), desktop or mobile; one device costs half the quota and becomes the headline
fresh	true forces a new measurement; otherwise a report from the last 10 minutes is reused
Report link	xspeedcache.com/scan/r/<id>; add .md for a Markdown twin an agent can read
Report visibility	Hub scans are filed unlisted; Scan MCP scans are public in the scan directory by default

Rules worth keeping

Read before you spend. Ask for the scan history first; start a new scan only when you want a fresh measurement or something changed.
A report link is not private. An unlisted report is kept out of the scan directory and search, but anyone with the URL can open it. A scan started through the Scan MCP is public by default.
run_speed_scan changes nothing on your site, but the Hub classes it a write, so a read-only connection (the connection token with Read-only everywhere on, or a Viewer sign-in) refuses it and your client may prompt for it. Use get_speed_scan, or the Scan MCP for a public URL, when you want a strictly read-only route.
Compare like with like. A scan that lost its Lighthouse run is marked partial and is not comparable with a full one, and the lab grade is not the same as real-visitor Core Web Vitals, which the report shows separately.
A scan cannot reach private, local or password-protected sites, and a site behind a bot challenge returns a report that says its server checks were not measured.

Good to know with GitHub Copilot in VS Code

VS Code starts in Manual permissions, so 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. If you allow run_speed_scan for the workspace or for all future calls, it stops asking, and every scan spends the shared speed-test allowance on the Hub. Allow All and Autopilot skip the prompts too. Chat: Manage Tool Approval groups tools by MCP server, so trust get_speed_scan there and leave run_speed_scan on a prompt. Also note that a scan measures the live site, so a pull request branch that is only on your machine or in an unmerged preview with no public URL cannot be scanned.

More prompts for this job

Prompts about your own sites work in any client connected to xSpeed Hub. A prompt that scans a site you do not run, or names the scan server, needs the xSpeed Scan MCP from the setup above.

Prompt

Using xSpeed Hub, what did the shop site score on its last speed scan? Do not start a new one.

Prompt

Use xSpeed Hub to run a speed scan on blog and give me the three fixes that recover the most points, plus the report link.

Prompt

With xSpeed Hub, scan only the mobile view of shop and tell me the grade.

Prompt

I changed the theme this morning. Use xSpeed Hub to run a fresh scan on docs and compare it with the previous report.

Prompt

Use the xSpeed Scan MCP to grade [competitor URL] and tell me what its biggest weaknesses are.

Prompt

The speed scan on shop is still running. Ask xSpeed Hub to check it again and tell me when it finishes.

Frequently asked questions

Only if the preview has a public URL that the xSpeed servers can reach. A scan runs from the xSpeed servers, so local, private and password-protected previews are not scanned. Use the Scan MCP for a public preview URL, or the Hub for a site in your workspace.

Because VS Code starts in Manual permissions and confirms any tool call that is not auto-approved, reads included. The Hub also classes run_speed_scan as a write tool: each scan spends the shared speed-test allowance, though it changes nothing on the site. The dialog is your Copilot client's own check. The Hub itself does not ask before it runs.

run_speed_scan runs the full xSpeed Scan: server probes plus Lighthouse, a 0 to 100 grade across four dimensions, the fix for every failing check and a shareable report link. run_speed_test returns a raw PageSpeed Insights score with Core Web Vitals and no graded report.

Yes, through the xSpeed Scan MCP at https://xspeedcache.com/scan/mcp. It needs no account and no sign-in, accepts any public URL and is read-only. The Hub route only scans sites you connected to your own workspace.

The Scan MCP allows 4 scans per caller per 10 minutes. Scanning the same URL again within 10 minutes returns the existing report unless the agent passes fresh: true. A Hub scan spends a shared allowance of the scan service, which is why the Hub treats it as a write tool.

Reports started from the Hub are filed as unlisted, which keeps them out of the public scan directory and search results, but the link itself still opens for anyone who has it. Reports started through the Scan MCP are public by default.

The headline grade is the desktop run, because it is the one you can reproduce in your own browser. The mobile run is graded on the same rubric and returned alongside it. Google ranks on mobile, so when the two differ the agent should tell you both.

Keep going

Scan a site's speed with other agents

More with GitHub Copilot in VS Code

Purge the cache Find out why pages are not cached Track PageSpeed scores Raise the PageSpeed score Tune cache settings Warm the cache Set up Redis object cache Manage Cloudflare Manage every site at once

Documentation

From the blog

Scan a site's speed, 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