There are a variety of possible causes for slowness in a Salesforce application. Many issues can resolved by troubleshooting the affected user's browser, internet connection, network, or mobile device settings.
Before contacting support, please review the troubleshooting resources below from Salesforce.
To diagnose and troubleshoot web browser issues, please follow the appropriate steps in the articles below:
If your user is still experiencing slow performance after following all of the above troubleshooting, please create a support ticket with our staff and provide the affected username, the exact page or url which is slow to load, and the troubleshooting steps you've already taken, so we can further assist.