Is Performance Max wasting my budget?

Blended ROAS is the number that hides the answer

Most founders judge Performance Max on the account’s blended return. That number averages two different jobs into one grade.

Here is a real example from my own book. Across two home-brand Shopify accounts over ninety days, the blended return came out to 21x. Nobody looking at that number asks whether anything is being wasted.

Split it by campaign type and the story changes. Standard Shopping took 18 percent of the spend and produced 52 percent of the revenue at 61x. Performance Max took 82 percent of the spend and produced 48 percent of the revenue at 12x. Shopping was harvesting demand that already existed. PMax was doing the expensive work of finding new buyers. The blended 21x hid a 5x gap between the two jobs.

Neither number means PMax was failing. 12x prospecting is strong for home goods. The point is that you cannot know until you separate the jobs.

Three signals the waste is real

The conversion signal feeding it is wrong. Performance Max is an amplifier. It optimizes toward whatever conversion data you give it, so broken purchase values, duplicate events, or missing checkout tracking send it shopping for the wrong customers at full price. In my audits this is the most common root cause, and it is invisible from inside the campaign screen. I wrote up the checks in the conversion tracking library.

It takes credit for demand you already owned. PMax serves on branded queries and remarketing pools by default. If your branded search or Shopping campaigns went quiet after PMax launched, some of its reported conversions moved over from cheaper campaigns rather than being created. I covered the mechanics in why Performance Max gets credit for Shopping conversions.

One campaign carries every product and audience. A single PMax campaign with one asset group across a whole catalog gives the algorithm nothing to differentiate. Margins, price points, and intent levels all get averaged, and the budget flows to whatever converts easiest rather than what earns most. I run a six-campaign PMax matrix on catalog accounts for exactly this reason.

How to run the split on your own account

1. Segment the last ninety days by campaign type. Note spend share and revenue share for PMax, Shopping, branded search, and non-brand search separately.
2. Pull the PMax search categories insight. If the top categories are your brand name and product lines you already rank for, PMax is harvesting, not prospecting, and should be judged against your harvest campaigns.
3. Compare each campaign type against its own job. Harvest campaigns should run several multiples above your blended target. Prospecting should clear your break-even ROAS, which is one divided by your gross margin, with room to spare.
4. Check the learning phase before judging anything. A new or heavily edited PMax campaign spends one to two weeks recalibrating, and cost per acquisition can run well above target during that window.

What a healthy PMax looks like

In the two accounts above, PMax prospecting ran between 8x and 17x depending on the brand, while the harvest layer ran far higher. If your PMax sits below break-even ROAS for thirty days or more with clean tracking and a stable campaign, that is waste, and the fix is structural rather than a bid change.

The fix order

Tracking first, structure second, creative third. Verify the purchase event, its values, and deduplication before touching the campaign. Then separate harvest from prospecting so each job gets judged and budgeted on its own numbers. Only then work the asset groups. Fixing them in the reverse order optimizes a campaign against data you cannot trust.