it depends where the ski is cracked, how big the crack is and what u want to/are using the ski for.
a small crack at the tail of the ski is not going to affect the skis performance.
however if the crack is under the sole (where it will be most of the time) then if it gets worse, you could feel a difference. i dont think there is a solution or cure for edge crack once it happend.
for rails the ski will still be dope, but for carving gs turns i think it will become less suitable.
my advice to you is, maybe use a rubber stone to get the edge very round, so you wont catch an edge, and maybe exchange the position of the ski i.e. the ski u used to have on your left foot you should put on your right foot.
as far as booters go, i dont think that u will notice a difference with a crack in the edge.
possibly, buy another ski which u will use for all mountain and booters, while the ski with the cracked edge u can use for urban and rails/boxes/jibs.
btw as long as its just a crack its not too bad, but once part of the edge rips out, you might really think of getting a new ski.
oh, short question, by chance, is this crack on a salomon suspect?
cuz edge problems happen alot by this model