The regeneration and sound bugs

The bug is :
1. When i play offline and online world sometime the world regeneration is too slow. Example : when i leave 1 chunk the other chunk don't regenerate
2. Sometime the sound are slow and disappeared. Example : when i get attack by hostile mob i don't hear any mob sound and the sound when i get hit by them. but i think this is because of the new audio setting.
I hope mojang will fix this bug