Q: keyboard slow at the login screen where I put my password.

Shut down your Mac and restart it in "Safe Mode". To learn how to do that please read: Try safe mode if your Mac doesn't finish starting up.

Determine if the same problems exist while operating in that mode, or not.

Then, restart normally. If the same problem returns, please read the section If an issue doesn't happen in safe mode for Apple's recommended actions.

First, refer to "Your keyboard has one or more keys that don't respond" in the following: If your Apple wireless mouse, keyboard, or trackpad aren't working as expected - Apple Support. Follow all those steps.

Also, please review the Accessibility setting for "slow keys" in the following: macOS Sierra: Use accessibility features.

Refer to the following: VoiceOver for Mac: Automatically use VoiceOver in the login window

Note the settings for both "Show input menu in login window" and "Use VoiceOver in the login window". Toggle either setting, or both of them. Log out and log in again. Test.