Anandtech: iPad uses 30% more RAM for the same tasks because of 64 bit
A lot of disgruntled iPad 1 owners will tell you lack of RAM is it's achilles heel, I hope this 30% increase in its RAM use with no increase in capacity doesn't hurt it.
People saying Mavericks like compression will help: Anand measured how much RAM was in use under load. If it was compressing something, it would have been factored into how much was used. Even if it is using compression, it's no magic cure.