We need some more information to help you.
- Were there any changes when the problem started?
- What Version of CM and SQL are you running?
- Did you check in MessageViewer if there are any unusual status messages?
- Did you check Performance Viewer (e.g. is the Disk usage high / disk latency, CPU, Mem)?
- Did you check if the Database is slow or CM (e.g. run a read query on the CM Database)?
- Is the Database Maintenance task active -> https://learn.microsoft.com/en-us/mem/configmgr/core/servers/manage/maintenance-tasks
- Are all components operating normally and showing a green status?
- Check the built in health reports in the Console