Finally! When play melee classes I always had problem with so much spell visual effects! In SL it seems that there will be an option to only see your own spells and essential ones (probably healers ground effects…)
VIDEO_OPTIONS_SPELL_DENSITY_ONLY_ESSENTIAL = "Only show essential spells. Your own spells are always shown.";
EDIT: it seems that it will also be a dynamic options to hide spell effects only when your FPS drops 
(if I understand this correct)
["spellClutter"] = {"-1", false, false, "Cull unimportant spell effects. -1 means auto based on targetFPS otherwise [0-100], 0 means cull nothing for perf reasons, 100 means cull as much as you can"},