Browser becomes extremely slow only on one Computer

Because several browsers are slow only on this PC while other devices work normally, investigate system resources, proxy, security, or adapter issues instead of reinstalling a browser. Open Task Manager and sort Processes by CPU, Memory, Disk, and Network; note sustained saturation. Check free space on drive C, restart Windows, and disable only unnecessary Startup apps. Then review Settings, Network & internet, Proxy and remove an unexpected manual proxy, but keep settings required by your organization. Update Windows and the adapter driver, then run a Defender scan. Test one browser in an InPrivate or Guest window. If Task Manager remains normal but every browser is slow, perform a clean boot; improvement there identifies a third-party service, filter driver, VPN, or security product. Re-enable items in groups until the slowdown returns. Use Network reset only after recording VPN and adapter settings, because it removes and reinstalls network adapters.