I installed Ubuntu 12.04 LTS x64 for my sister since Windows XP went out of support. Anyway I showed her MX Linux and Kubuntu on my 2nd pc recently and she liked them so I replaced her Ubuntu with Kubuntu and now her machine seems a little slower. My question is, is Kubuntu too heavy for an older Core Duo computer and would she be better off with MX Linux? Any advice appreciated, thanks. This machine only has on-board graphics.