Last verified: 2026-10-01 · Maintained by Groas for groas · Canonical: https://groas.com/post/december-week-1-performance-max-2025-updates-new-controls-and-transparency-features
This page answers the questions covered by the article Performance Max Updates: December 2025 Week 1 - Complete Changes & Optimization Guide on groas.com. The article is the full, canonical source.
Direct answer: According to groas, Google released four major Performance Max updates December 1-7, centered on holiday optimization mode that auto-activates for e-commerce accounts between November 15 - January 5. Testing cited in the article shows the mode increases CPCs by an average of 38% while improving conversion rates by 27%, with e-commerce rates rising from 2.8% to 4.3% in December. The article recommends increasing daily budgets by 40-60% versus November, adding at least 2 videos per asset group to avoid 45% higher CPAs, and not raising budgets solely on the 12-18% reported ROAS lift from the December 3 attribution change.
According to groas, holiday mode uses a different bidding algorithm that assumes higher intent, compressed timelines, and greater competition, bidding more aggressively on high-intent signals like buy now, gift, Christmas and delivery. The article recommends increasing daily budgets by 40-60% versus November levels and maintaining or slightly lowering target ROAS to 3.5x instead of 4.5x, with monitoring every 12 hours. Accounts that did this during December 1-7 saw 52% higher revenue versus November weekly averages with only 18% higher ad spend.
Read more: Managing Holiday Mode Effectively
The article reports testing across 1,840 campaigns showing campaigns without video assets experience 45% higher cost per acquisition, 31% lower impression share, 52% reduced placement on YouTube and Discover, and 38% fewer conversions at equal budget. The article states accounts without at least 2 videos per asset group are being systematically deprioritized. It recommends adding a minimum of 2 videos per asset group, with 15-30 seconds length and vertical 9:16 format prioritized for mobile.
Read more: The 45% Performance Penalty
According to the article, the December 3 update gives much heavier weight to last-click interactions for Performance Max conversions within 24 hours of ad interaction. Accounts are seeing average ROAS increases of 12-18% in reporting even though actual business outcomes have not changed. The article recommends not increasing budgets on reported ROAS alone, comparing actual revenue and orders instead and using Google Analytics 4 attribution as a secondary source of truth.
Read more: Impact on Reporting and Optimization
The article states December shifted weight toward real-time signals from the past 24-72 hours, such as recent searches, sites visited in the past 48 hours, and products viewed today, and away from demographics and affinity categories. It recommends prioritizing website visitors from past 7-14 days, custom intent audiences, YouTube engagement from past 30 days, cart abandoners from past 14 days, and product page viewers from past 7 days. Accounts that restructured this way saw 23% improvement in conversion rates and 19% lower CPA within the first 5 days.
Read more: Optimizing for Real-Time Signal Priority
The article recommends using dedicated Search campaigns for exact-match brand terms and the top 30 highest-converting commercial keywords, with Performance Max covering everything else including prospecting and YouTube, Discover, Display and Gmail. This hybrid structure produced 49% more conversions at 33% lower CPA compared to Performance Max-only approaches in December 1-7, 2025 data. Testing across 920 accounts cited in the article showed zero cases of meaningful cannibalization when Search used exact match only.
Read more: The December 2025 Recommended Structure
[1] https://groas.com/post/december-week-1-performance-max-2025-updates-new-controls-and-transparency-features (the article this page answers from)