Kikat is supposed to run well on phones with 512 MB or greater RAM.
JB could work on low RAM memory devices. It is possible to upgrade but only under custom ROMS. Installing them voids your warranty of phone and there is a risk of getting soft/hard brick. Brick actually means your phone is now piece of brick and cant be used. Soft brick can be solved but hard maybe not.
You can search on google "custom rom for <your phone name>
Kikat is supposed to run well on phones with 512 MB or greater RAM.
JB could work on low RAM memory devices. It is possible to upgrade but only under custom ROMS. Installing them voids your warranty of phone and there is a risk of getting soft/hard brick. Brick actually means your phone is now piece of brick and cant be used. Soft brick can be solved but hard maybe not.
You can search on google "custom rom for <your phone name>