Duplicate thread of: How i can make zorin lite doesn't login until all startup apps open?
The first suggestion I would make is - Cleanup your startup programs.
The possible configurations you can use with LightDM are listed in the summary below:
Summary
—Appearance:
theme-name = GTK+ theme to use
icon-theme-name = Icon theme to use
background = Background file to use, either an image path or a color (e.g. 772953)
user-background = false|true (“true” by default") Display user background (if available)
transition-duration = Length of time (in milliseconds) to transition between background images (“500” by default)
transition-type = ease-in-out|linear|none (“ease-in-out” by default)
----Fonts:
font-name = Font to use
xft-antialias = false|true Whether to antialias Xft fonts
xft-dpi = Resolution for Xft in dots per inch (e.g. 96)
xft-hintstyle = none|slight|medium|hintfull What degree of hinting to use
xft-rgba = none|rgb|bgr|vrgb|vbgr Type of subpixel antialiasing
—Login window:
active-monitor = Monitor to display greeter window (name or number). Use
cursor value to display greeter at monitor with cursor.
position = x y (“50% 50%” by default) Login window position
default-user-image = Image used as default user icon, path or #icon-name
hide-user-image = false|true (“false” by default)
—Panel:
panel-position = top|bottom (“top” by default)
show-clock = false|true (“false” by default)
clock-format = strftime-format string, e.g. %H:%M
show-indicators = semi-colon “;” separated list of allowed indicator modules. Built-in indicators include “~a11y”, “~language”, “~session”, “~power”. Unity indicators can be represented by short name (e.g. “sound”, “power”), service file name, or absolute path
—Accessibility:
a11y-states = states of accessibility features: “name” - save state on exit, “-name” - disabled at start (default value for unlisted), “+name” - enabled at start. Allowed names: contrast, font, keyboard, reader.
keyboard = command to launch on-screen keyboard (e.g. “onboard”)
keyboard-position = x y[;width height] (“50%,center -0;50% 25%” by default)
reader = command to launch screen reader (e.g. “orca”)
—Security:
allow-debugging = false|true (“false” by default)
screensaver-timeout = Timeout (in seconds) until the screen blanks when the greeter is called as lockscreen
—Template for per-monitor configuration:
[monitor: name]
background = overrides default value
user-background = overrides default value
laptop = false|true (“false” by default) Marks monitor as laptop display
As you can see, there is no possible method of extending the login Window until after all startup-listed programs are active.
You might check your RAM.
And remove non-essential items from your start up.
You can check if there are delays on any startup entries configs... For example, I delay my Conky Startup by 20 seconds in order to allow other startup services full resources before initializing conky.