ATLauncher allows you to change the amount of memory/ram that is used when launching Minecraft. By allocating more memory/ram, you should see better performance with Minecraft (To a certain point), and will entirely depend on the amount of total memory/ram you have and what applications you have open.
You can change the amount of memory/ram that's used to launch Minecraft either globally for all instances, or on a per instance basis. If you set it globally.
To change memory/ram globally for all instances, see below:
Thanks to ATLauncher for letting me use this image
To change memory/ram for a single instance, see below:
Thanks to ATLauncher for letting me use this image
Text and images taken from ATLauncher help page i do not claim ownership of the content on this page