the editor requires huge resources...it's because it has such a big database, when you load it ALL the data the game has is loaded, every player, every club, stadium, competition. if you have less than 512mb RAM it's not recomended to use it i think.
and i don't think you're able to change then names of the competitions. they don't have the rights to use those names so you're stuck with champions cup, not the champ. leauge, don't know what the big deal is to be honset.