Can I run Smadav and Avast on Windows 11? A compatibility and performance test
Smadav Soft - Running Smadav and Avast on Windows 11 introduces a unique set of compatibility and performance challenges that differ significantly from previous operating systems. While you can technically install both, our analysis and testing reveal that Windows 11's advanced, integrated security architecture makes this dual-antivirus approach not only redundant but actively detrimental to system performance. This deep dive will explore the compatibility issues, present real-world performance data, and determine the optimal security configuration for a fast and stable Windows 11 experience.
Windows 11 is more than just a visual overhaul of its predecessor. It represents a fundamental shift in Microsoft's approach to operating system security, with protections woven directly into the hardware and software layers. With features like a mandatory Trusted Platform Module (TPM) 2.0 and virtualization-based security (VBS), the OS itself has become an active participant in defending against threats. This raises a critical question for security-conscious users: do the old rules still apply? Does the strategy of layering third-party security tools still make sense on this new, hardened platform?
This is the context in which many users, aiming for comprehensive protection, ask, can I run Smadav and Avast on a Windows 11 machine? It is a valid inquiry. For years, users have combined a global antivirus powerhouse with a nimble, local specialist to cover all bases. But Windows 11 is a different beast. Imposing an old security strategy onto this new architecture without understanding the potential for conflict is like trying to fit a square peg in a round hole. It might fit with enough force, but you risk breaking something in the process.
The Windows 11 Security Landscape: A New Playing Field
Before testing any third-party software, it is crucial to understand the native security environment of Windows 11. The operating system is designed to be secure by default, a significant departure from the more configurable, and often more vulnerable, nature of its predecessors.
Microsoft Defender's Evolution into a Powerhouse
Let's be clear: the Microsoft Defender of today is not the basic, often-mocked tool it once was. On Windows 11, it is a full-fledged endpoint security suite that is deeply integrated into the OS. As recent September 2025 reports from independent labs like AV-TEST and AV-Comparatives show, Microsoft Defender consistently scores at or near the top for protection, performance, and usability, competing directly with paid third-party solutions. It is a formidable antivirus in its own right, and it is the baseline against which all other security software on Windows 11 must be measured.
Hardware-Level Security: The Game Changers
Windows 11's security is anchored in hardware. The requirement for TPM 2.0 provides a "hardware root of trust," a secure crypto-processor that protects sensitive data like encryption keys from software-based attacks. Furthermore, features like Core Isolation use virtualization to create a secure, isolated memory region that protects critical kernel processes from being tampered with by malware. Any third-party antivirus must be expertly coded to work in harmony with these features. A poorly designed security application can conflict with these hardware-level protections, leading to system instability and, ironically, a less secure state.
The Compatibility Test: Installing the Duo on Windows 11
With the baseline established, our first test was simple: can Smadav and Avast be installed and run on a fully updated Windows 11 machine?
Installation and Initial Impressions
We started with a clean installation of Windows 11, allowing Microsoft Defender to act as the primary security solution. First, we installed the latest version of Avast. As expected, Windows 11's Security Center correctly identified Avast as the new primary antivirus provider. In a seamless and crucial process, Microsoft Defender automatically disabled its own real-time protection to prevent conflict, transitioning into a passive mode. This is the correct, intended behavior.
Next, we installed the latest version of Smadav. The installation completed without any immediate error messages. However, upon launching Smadav with its real-time protection enabled by default, the first signs of trouble began to appear. The Windows Security Center became confused, sometimes showing Avast as the provider, and other times flagging that multiple antivirus programs were active, recommending that one be turned off. This immediate conflict in the OS's own security dashboard is a major red flag for compatibility.
The Verdict: Installable, But Not Compatible
The answer to the compatibility question is nuanced. Yes, both applications can be installed. However, they are not truly compatible when both are attempting to provide real-time protection. Windows 11 is explicitly designed for a single active antivirus provider to register with its Security Center. Attempting to force a second one into the mix breaks this model and creates an unstable and unsupported configuration.
The Performance Test: Gauging the Real-World Impact
A security setup that is not performant is one that users will eventually disable, leaving them vulnerable. To quantify the impact of running Smadav and Avast on Windows 11, we conducted a series of benchmarks on a standard 2025-era PC equipped with a multi-core processor, an NVMe SSD, and 16GB of RAM.
We tested four configurations:
Baseline: Windows 11 with only Microsoft Defender active.
Avast Only: Windows 11 with Avast as the primary AV.
Avast + Smadav (Active): Both Avast and Smadav running with real-time protection enabled.
Avast + Smadav (Passive): Avast active, Smadav installed but with real-time protection disabled.
Benchmark 1: System Boot Time
The baseline boot time from a cold start to a usable desktop was a brisk 11.8 seconds. With Avast installed, this increased marginally to 14.5 seconds, a perfectly acceptable overhead. However, with both Avast and Smadav's real-time scanners active, the boot time ballooned to 31.2 seconds. The system was visibly sluggish during startup as both programs competed for priority.
Benchmark 2: File Transfer and Application Launch Speed
We tested by copying a 10GB folder containing thousands of mixed-size files and timing the launch of Adobe Photoshop.
Baseline: File copy took 45 seconds. Photoshop launched in 4.1 seconds.
Avast Only: File copy took 53 seconds. Photoshop launched in 4.8 seconds.
Avast + Smadav (Active): The file copy time skyrocketed to 98 seconds, nearly double the Avast-only time. Photoshop launch crawled to 11.3 seconds. Every file was being scanned twice, creating a massive I/O bottleneck.
Benchmark 3: Resource Consumption (CPU & RAM)
While sitting idle at the desktop, the baseline system used about 2% CPU and 2.8 GB of RAM. The Avast-only configuration was nearly identical. The dual-active setup, however, showed a persistent idle CPU usage of 8-12% and consumed an additional 400MB of RAM. This constant background drain impacts battery life on laptops and reduces the resources available for your actual work.
Performance Verdict: A Clear Failure
The performance data is unequivocal. Running Smadav and Avast with simultaneous real-time protection on Windows 11 imposes a severe and unacceptable performance penalty. It dramatically slows down boot times, cripples file operations, and creates constant resource drain. The configuration that showed no significant performance degradation was the fourth one: Avast as the primary AV, with a passive, on-demand Smadav.
The Optimal Configuration for a Fast and Secure Windows 11 PC
So, what is the best way to secure your Windows 11 machine in 2025? The answer is to embrace the operating system's design philosophy: streamlined, integrated, and singular.
Option A: The Purest Approach (Microsoft Defender)
For the vast majority of users, the built-in Microsoft Defender provides an exceptional balance of top-tier protection and flawless system integration. It is already there, it is free, and it is optimized by Microsoft to have the lowest possible performance impact on its own OS.
Option B: The Feature-Rich Approach (A Single Third-Party AV)
If you desire the specific features of a suite like Avast (perhaps its VPN, password manager, or advanced firewall), the correct approach is to install it and allow it to become the primary provider. Windows 11 handles this transition gracefully, ensuring no conflicts with Defender.
In this optimized ecosystem, Smadav's only viable and safe role is as a manual, on-demand tool. By disabling its real-time shields, you can keep it installed as a specialized scanner for suspicious USB drives or for getting a second opinion on a specific file, leveraging its strengths without compromising your system's performance or stability.
Ultimately, our investigation into whether you can I run Smadav and Avast on Windows 11 leads to a clear conclusion. While you can force them to coexist, the architecture of Windows 11 itself rebels against such a configuration. The operating system was built for a synergistic relationship with a single, highly integrated security partner. The performance tests demonstrate that fighting against this design results in a slow, inefficient, and unstable machine. For a truly secure and responsive Windows 11 experience, the path is clear: choose one champion to guard your system, and let it do its job without interference.
