This very pack would be your way to go, should the computer you're using isn't that powerful.
Considering it's derived from Default 3D High. In comparison, it lacks quite a few block models and features pack-specific block models instead. This ensures the pack will run as smooth as it possibly can.
All pixels on any edge of any model element connect seamlessly with the pixels of its adjacent face, creating a visually pleasing experience.
Download: Default 3D Low