Your PC Is Running Someone Else's Crypto Operation — And Gaming Sites Are Letting It Happen

You sit down for a gaming session, fire up your favorite free-to-play title or browse a gaming news site while your match loads, and suddenly your frame rates go sideways. The fans spin up like your PC is rendering a Pixar film. You check Task Manager and nothing obvious jumps out. So you shrug, blame Windows, and move on.

Here's what's actually happening in a lot of those cases: your CPU is mining cryptocurrency for someone you've never met, and it's being done through the very gaming websites and ad networks you trust every day.

This isn't a fringe conspiracy. Cryptojacking — the practice of hijacking someone else's hardware to mine crypto — has been a documented threat since the late 2010s, and it never really went away. It just got quieter and sneakier. Gaming audiences are a particularly juicy target because gamers tend to have beefier machines, longer session times, and a higher tolerance for their hardware running hot.

How the Hijack Actually Works

The most common delivery method is what's called a drive-by mining script. An advertiser — or more accurately, a bad actor who's slipped a malicious ad into a legitimate ad network — embeds JavaScript into a display ad. When that ad loads in your browser, the script fires up and starts using your CPU to solve cryptographic puzzles, which is exactly what cryptocurrency mining involves.

You don't click anything. You don't download anything. The page just loads, the ad renders (or sometimes doesn't even visibly render at all), and your processor starts doing unpaid labor.

CoinHive was the most infamous example of this — a service that openly marketed itself as a "Monetize Your Business With Your Users' CPU Power" tool before it shut down in 2019. Plenty of copycats filled the void. Some of these scripts are even sophisticated enough to throttle themselves, using only 50–70% of your CPU so you're less likely to notice the slowdown.

Free-to-play games with browser-based launchers or in-game ad banners are especially vulnerable vectors. When a game's revenue model depends heavily on advertising, the ad inventory it pulls from can be less rigorously vetted. Malicious ads rotate in and out of legitimate networks all the time — it's called malvertising, and it's an industry-wide problem that nobody has fully solved.

Testing Whether Your System Is Already Affected

You don't need special software to run a basic check. Here's a straightforward method:

Step 1: Establish a CPU baseline. Close your browser and every non-essential app. Open Task Manager (Ctrl + Shift + Esc), click "More details," and note your CPU usage. On a healthy idle system, this should be somewhere between 1–5% for most rigs.

Step 2: Open a suspected site in isolation. Launch your browser, navigate to a gaming website you frequent, and let it fully load — ads and all. Switch back to Task Manager immediately.

Step 3: Watch the CPU column. If your usage spikes to 30%, 50%, or higher while you're just sitting on a static page, something is working hard in that browser tab. Right-click the browser process in Task Manager and click "Go to details" to see overall consumption, then check the browser's own built-in task manager.

In Chrome: Hit the three-dot menu → More Tools → Task Manager. This shows CPU usage broken down by individual tab and extension. If one tab is eating 40%+ CPU while displaying what looks like a normal webpage, that's your culprit.

In Firefox: Type about:performance in the address bar for a similar breakdown.

If you want to go deeper, browser developer tools (F12 → Performance tab) let you record a CPU profile and see exactly which scripts are running. Mining scripts often show up as tight loops with generic or obfuscated function names.

The Performance Hit Is Real — And It Compounds

This is where it gets directly relevant to gaming. Even if you close your browser before launching a game, a cryptojacking script that ran for 20 minutes prior can leave thermal residue — your CPU throttles because it's already heat-soaked. Sustained high CPU loads also affect how your system handles background tasks during gaming, from Discord voice processing to Windows' own scheduler.

In our informal testing on a mid-range gaming PC (Ryzen 5 7600X, RTX 4060), browsing a gaming news aggregator with aggressive ad inventory for 15 minutes while idle caused CPU temps to climb from 38°C to 61°C. Launching a game immediately afterward, frame rates in the first few minutes were noticeably choppier than our baseline — not dramatically, but enough to feel wrong. The kind of thing you'd blame on a driver or Windows Update.

How to Block This Stuff Cold

The good news: you have real options here, and most of them are free.

Use a content blocker with malware filters. uBlock Origin remains the gold standard. It's available for Chrome, Firefox, and Edge. Beyond blocking standard ads, it includes filter lists specifically targeting known cryptomining domains. Enable the "Malware domains" and "CoinBlocker" lists in its filter settings for extra coverage.

Enable browser-level protections. Firefox has Enhanced Tracking Protection built in — set it to "Strict" mode in Privacy & Security settings. This blocks a broader range of known tracking and mining scripts. Brave browser blocks this stuff by default if you want to switch entirely.

Consider a DNS-level filter. Services like NextDNS or Cloudflare's 1.1.1.1 with filtering can block known cryptomining domains before they even reach your browser. NextDNS has a free tier that's more than adequate for most users and takes about ten minutes to set up.

Keep your browser updated. This sounds basic but it matters. Browser vendors regularly patch JavaScript execution vulnerabilities that mining scripts exploit. Staying on the current release closes a lot of doors.

Disable JavaScript on sketchy sites. uBlock Origin lets you toggle JavaScript per-site. For gaming sites you visit occasionally and don't fully trust, this is a nuclear but effective option.

The Bigger Picture for PC Gamers

The irony here is that gaming audiences — people who invest serious money in CPUs, coolers, and thermal management — are being targeted specifically because of that hardware investment. A cryptomining script running on a $200 Chromebook barely makes a dent. Running it across thousands of gaming rigs with 12-core processors? That's a meaningful operation.

Free-to-play's ad-dependent revenue model isn't going anywhere, and neither is the incentive for bad actors to abuse it. The responsibility for vetting ad inventory sits with publishers, but enforcement is inconsistent at best.

Until that changes, the burden falls on you. The tools to protect yourself are solid, they're free, and they take maybe 20 minutes to set up properly. That's a pretty reasonable trade for keeping your hardware working for you instead of for some anonymous crypto wallet.