Quiz and Memchached

I'm not quite sure if I should ask this here or on the memcache module. I'm sorry if it's the wrong place.

Does it make sense to use caching for quizzes? I saw in other issues that there can be problems when using caching on the quizzes but everything is working fine for me with memcached. But the amount of memory filled by memcached is much higher than I expected and it seems it doesn't stop to become more and more. So I wonder, is it caching every questen every time a quiz is taken seperately because of different values of quizkey? If that's the case it doesn't make any sense to cache the pages of quizzes at all.