To use memory (ramdisk) for the the drive /tmp storage, edit

sudo nano /etc/default/tmpfs

Set your default limit in bytes (here 548MB)

shm=573741824

Then add to the startup routine

sudo nano /etc/fstab

...add this line to the end of the file, save & reboot

tmpfs /tmp tmpfs defaults,noexec,nosuid 0 0

On reboot, when you run df -h to see your disk allocations you'll see /tmp mounted into a ramdisk tmpfs partition.

Or more comprehensively

tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0
tmpfs /var/tmp tmpfs defaults,noatime,mode=1777 0 0

Please note that if your machine dies halfway thru anything inside the /tmp drive will be lost.