Sometimes, it is possible to improve the performance of Ubuntu on older hardware by modifying the disk swapping behavior.
Check your current setting:
cat /proc/sys/vm/swappiness
To modify the behavior, just change the value and reboot. Most documentation recommends trying a value of 10.
sudo vi /etc/sysctl.conf
Add (or change):
# Decrease swappiness value (default:60)
vm.swappiness=10
REFERENCES: