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If you have an older computer, choosing the right antivirus is critical. Some antivirus software is so resource-intensive it can make old PCs unusable. Here’s the best lightweight antivirus for older systems in 2025.
System Requirements to Look For
- Less than 100MB RAM usage during idle
- Low CPU impact during background scanning
- Small installation footprint
- Quick scan capability
- Option to disable real-time protection when needed
Top Lightweight Antivirus for Old PCs
- Webroot SecureAnywhere – Uses only 5MB RAM, cloud-based (9.0/10)
- ESET NOD32 – Legendary for low resource usage, excellent protection (9.2/10)
- Windows Defender – Integrated, minimal overhead (8.5/10)
- Comodo Internet Security – Free, lightweight (8.1/10)
- Avira Free Security – Lightweight with optional cloud detection (8.3/10)
Tips for Old PC Security
- Run quick scans instead of full scans
- Enable “Gaming/Silent Mode” during work
- Schedule scans for when you’re away
- Consider Webroot for the lightest possible footprint
- Keep your OS updated even on old hardware
