Run GNS3 on Windows/Mac but offload emulation to a Linux VM. This yields 30–50% better performance.
“GNS3 vs EVE-NG: Which Emulator Handles Router Images Better?” gns3 router images
These are original files from older physical routers like the Cisco 7200, 3725, or 2600 series. GNS3 uses the Dynamips emulator to run these images. While they are lightweight and easy to set up, they generally run older versions of IOS (like version 12.x) and may lack modern features. Run GNS3 on Windows/Mac but offload emulation to a Linux VM