Windows 11 24H2: Clean Install vs. In-Place Upgrade Performance Analysis

Windows 11 users, it's that time again. A new feature update, Windows 11 24H2, has rolled out with numerous enhancements and updates—but also a heated debate on whether upgrading in-place or going all-in on a clean installation delivers better performance. If you've been burned by those pesky performance bottlenecks or subtly slower systems after upgrades, this extensive comparison from Neowin may feed your need for tech analysis. Let us distill the insights, throw in some textured explanations, and walk you through the world of clean setups, in-place upgrades, and what they mean for your beloved PC.

Setting the Stage: Clean Install vs. Upgrade​

Before delving into the nitty-gritty, let's ensure we're all on the same page regarding the difference between these two paths:

• In-Place Upgrade: This is the "keep your apps and settings intact" method. It replaces your current OS version while attempting to retain all your personal files, settings, and installed applications. It's designed to minimize downtime and hassle.
• Clean Install: This method involves wiping your disk (or reformatting it) and starting fresh. Think of it as Marie Kondo-ing your PC—clearing out clutter that no longer sparks joy, including hidden junk and legacy files leftover from past updates.

Each approach comes with its own set of merits and pitfalls, and Neowin's recent benchmarking tests on Windows 11 24H2 versus 23H2 aim to answer which route impacts performance the least—or perhaps, delivers specific hidden gems.

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Key Takeaways from the 24H2 Performance Benchmarks​

After exhaustive testing using both synthetic benchmarks and real-world scenarios, a mixed bag of results emerged. Here’s how things panned out:

Gaming Performance: FPS Highs but Single-Thread Performance Lows​

Gamers, pay attention. While 24H2 reliably showed a marked boost in frame generation performance (a whopping 17% improvement) for the game Black Myth: Wukong when compared to 23H2, an unfortunate drop in single-threaded performance may burst your bubble. Single-threaded performance is crucial for older or less-optimized games and some applications.

• On a Clean 24H2 Install: The DirectX 11 and DirectX 12 tests (Fire Strike and Time Spy benchmarks) improved single-thread processing by nearly 8.2% and multi-threaded tasks by a margin of 5.87%. That’s promising but still does not necessarily translate into FPS boosts in certain games.
• For GPU-Intensive Titles: Interestingly enough, differences in GPU performance (especially with AMD's RX 7800 XT) were negligible, falling within margins of error (~2.23%). Whether you upgrade or clean install, the GPU’s rendering prowess didn’t show dramatic swings either way.

Reality Check: If you’re primarily gaming, the performance deltas between clean installs and in-place upgrades are minor. But keep an eye out for Core Isolation and Virtualization-Based Security (VBS)—features enabled by default on clean installs, which may cause slight CPU bottlenecks if left unchecked.

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Productivity and App Load Speeds: A Tough Pill to Swallow​

For professional users working with loads of applications or multitasking galore, the findings for 24H2 might rub you the wrong way. PCMark 10 benchmarks revealed a drop in application startup times—and not by just a sliver:

• 23H2 Metrics: Scored 24,096 points for app startups.
• Upgrade to 24H2: Slumped to 21,376 points (~11.3% slower).
• Clean Install on 24H2: Dropped further to 20,813 points (~13.6% slower).

On a clean install, even other productivity segments like spreadsheet processing, photo editing, and writing tasks fared worse than both 23H2 and 24H2 upgrade metrics.
Possible Explanation: These regressions may stem from broader optimization challenges linked to kernel tuning in 24H2. Anecdotally, Microsoft has had difficulties optimizing forced upgrades, especially when Core Windows subsystems undergo tweaks.

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Memory Allocation and System RAM Efficiency: The Bright Spot​

Interestingly, clean installs nailed memory efficiency compared to their upgraded counterparts—a significant win for users grappling with memory hogging issues. Tests revealed systemic reductions in cached page files, game/app data prefetch, and more.

• Clean Install Memory Metrics: Consistently lower system RAM usage than in-place upgraded 24H2 installations.
• In-Place Upgrade Issue: The "memory leak-like" behavior seen post-upgrade wasn't evident on freshly installed 24H2 systems, suggesting clean installs resolve lingering memory inefficiencies.

Implication: If system RAM allocation feels precarious post-23H2 upgrade, consider blowing the dust off your USB drive for a clean reinstall.

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Synthetic Benchmarks: The Science of Performance Gains​

Synthetic benchmarking tools such as Cinebench 2024 and 3DMark reiterated the general sentiment—they slightly favor clean installs, especially when testing multi-thread efficiency and CPU rendering tasks. However, gains hovered within small ranges (a handful of percentage points), which begs the question: do these marginal differences justify the effort and risk of wiping systems clean?
The real kicker? GPU rendering tests leaned in favor of clean installations for heavy computational scenarios but only marginally—hardly the deal-maker most were hoping for.

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Verdict: To (Clean) Install or Not to Install?​

Neowin's evaluation underscores a frustrating reality: for most users, there’s no clear-cut win for clean installs versus in-place upgrades—especially for typical workloads. However, specific cases such as mitigating memory inefficiencies or satisfying the performance zealot in you might still justify the clean path:

Who Should Clean Install 24H2?​

• Users experiencing RAM hogging or memory leaks post-upgrade.
• Those running hardware that benefits from clean driver setups (e.g., high-end GPUs or complex multi-drive solutions).
• Gamers or productivity-heavy users annoyed by lingering compatibility tidbits or slowdowns post-in-place upgrade.

Who Can Stick to In-Place Upgrades?​

• Users happy with 23H2 and already on rock-solid systems where app startups and multitasking reign supreme.
• Systems actively configured with intricate setups and proprietary/legacy software installations, where fresh installations might wreak havoc.

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Got Your USB Stick Ready? Why Preparation is Critical​

If you’re diving into a clean install, always:

• Backup Your Data: Whether it's OneDrive, external drives, or ISO images, secure everything critical before the plunge.
• Prepare All Drivers: From GPU to chipset, ensure you grab the latest drivers and put them on a USB drive.
• Disable VBS (if necessary): Check whether Virtualization-Based Security is slowing your system for non-corporate scenarios.
• Try Smaller Dataset Testing: Use tools like PCMark 10 or 3DMark post-installation to validate your observed gains.

Both paths—upgrading or clean installing—are valid in their own right. Yet, it all boils down to personal requirements and expectations. With 24H2, the bold effort to standardize memory efficiency might win over previously frustrated users. Still, for many, the performance regressions in productivity tasks and several key gaming scenarios put clean installation results on shaky footing.
Got thoughts? Share your experiences with in-place upgrades vs. clean installs on our forums and let the community know if your 24H2 install lived up to the hype—or let you down.

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Source: Neowin https://www.neowin.net/reviews/windows-11-24h2-vs-23h2-performance-benchmark-in-2025-clean-install-vs-in-place-upgrade/