To isolate the problem, please uninstall SQL Prompt and test if SSMS is still slow. If so, reinstall SQL Prompt. If the problem persists with the latest version (Help > Check for updates), please try the following steps:
- Disable Code Analysis function (SQL Prompt > uncheck “Enable Code Analysis”) and test again; if the problem disappears, it suggests that "Code Analysis" is the culprit, so please contact Support.
- Disable the built-in intellisense under Options > Text Editor > Transact-SQL > Intellisense
- Go to SQL Prompt > Options, click on Export to save your settings, and then try a "Restore all defaults".
- Disable the auto-refresh experimental feature (SQL Prompt > Options > Labs > Experimental features).
- If your SSMS version is below 17.3, you can raise the amount of RAM available for SSMS by using the Large Address Aware utility on ssms.exe (see https://www.techpowerup.com/forums/threads/large-address-aware.112556/).
- If the slowness occurs on startup, try disabling Tab History (SQL Prompt > Options > Tabs > History > Enable Tab History).
Note: If it's Object Explorer that's slow, this is more likely caused by SQL Source Control. Please see here for troubleshooting steps.
If the problem persists, enable verbose logging, reproduce the issue, log a ticket with Support and attach the log file for further investigation.