Check Task Manager for CPU, RAM, disk, and network spikes
Check Resource Monitor for the exact process causing the spike
Check Event Viewer for system and application errors
Check Device Manager for driver issues
Check Windows Update history for recent changes
Check startup programs and disable unnecessary ones
Check running background apps and services
Check antivirus or malware scans for infections
Check disk health with SMART tools or CHKDSK
Check temperature with hardware monitoring software
Check GPU usage and driver status
Check network latency with ping and traceroute
Check Wi-Fi signal strength and router logs
Check game or app logs for errors
Check recent software installs or updates
Check for overheating or thermal throttling
Check power settings and performance mode
Check cable connections and hardware seating
Check for failing RAM with memory diagnostics
Check for storage bottlenecks on HDD or SSD
Check browser extensions and open tabs
Check background downloads, syncing, and cloud backups
Check server status if the lag is online-only
Check FPS, frame time, and packet loss if gaming
Check system uptime and whether the issue appears after long use