Google Ads Performance Max: Using It Without Losing Control

Performance Max is Google's automation product combining its entire inventory (Search, Shopping, YouTube, Display, Discover, Gmail, Maps) into a single campaign. Powerful — but set up with defaults, you cannot see where your budget goes.

Before setup: is measurement correct?

Performance Max relies entirely on conversion signals. If your measurement is wrong, the algorithm optimises in the wrong direction and it takes weeks to notice. Verify three things before starting:

• Are conversions sent with value? "A purchase happened" is not enough; the order value must come through.
• Is there duplicate conversion counting? If the same transaction is counted by both the GA4 and Ads tags, targets inflate.
• Are micro-conversions ("page view", "spent 3 minutes") marked as primary conversions? If so, remove them.

Structure: separate brand traffic

Performance Max is very good at finding the cheapest conversion — and the cheapest conversion is almost always someone already searching for your brand. That is not real gain; it is buying traffic you would have received anyway.

The fix has two steps:

1. Build a separate Search campaign for brand keywords using exact match.
2. Add brand terms as account-level negatives for the Performance Max campaign (you can request a brand exclusion list from your Google representative).

Once you make that separation, Performance Max's true performance becomes visible. In most accounts, that is where the first shock arrives.

Asset group architecture

Instead of one giant asset group, build groups whose audience and message genuinely differ. Good criteria for splitting:

• Product category (where margins differ meaningfully)
• User intent (new customer versus existing customer)
• Geography (where language or currency differs)

Give each asset group at least 5 headlines, 5 long headlines, 5 descriptions, images in 4 aspect ratios and, where possible, a video. If you do not supply a video, Google generates an automatic slideshow — which usually damages brand perception.

Audience signals

Audience signals are a starting hint, not a restriction. The algorithm begins there and then expands. The most valuable signals come from your own data:

• Customer list (existing buyers → builds a similar audience)
• Site visitors, especially cart abandoners
• A high-value customer segment (LTV-based)

Five ways to keep control

1. Brand exclusion. As described above — the single most important intervention.
2. Account-level negative keywords. Block terms like "free", "jobs", "complaints".
3. Placement exclusions. Turn off children's apps and low-quality mobile game inventory.
4. Conversion value rules. Assign higher value to new customer acquisition than to existing customers.
5. Search term report monitoring. Limited as it is, review it weekly; add negatives when irrelevant categories appear.

When should you intervene?

The most common mistake with Performance Max is over-intervention. The rule: make no change without statistical significance. Deciding an asset group is underperforming needs at least 30 conversions or 4 weeks of data.

Make budget changes in steps of no more than 20%, once a week. Do not change target ROAS more than once a month.

Reporting: what to look at

Campaign-level ROAS alone is misleading. Look at three breakdowns:

• Non-brand ROAS — the indicator of real performance
• New customer rate — are you growing, or harvesting existing demand?
• Cost per conversion by asset group — shows where budget is drifting

An account that tracks these three numbers stops treating Performance Max as a black box.