Any login items, associated with your user account, will attempt to load immediately after you enter your password and press the enter key. One or more of these may be what is causing the delay.
You can temporarily disable all of these login items, by holding down the shift key, after enter your password, but BEFORE you press the enter key. It should make a difference. If so, you will need to review each of your login items to see which ones you still really need to use.
To do so, go to System Preferences > Users & Groups > Select your user account > Login items tab. Here you will find a list of any login items associated with your user account. Select any you don't still need, and then, click on the "-" (minus) button to remove them.