The increasing demand on higher accuracy and the rapid growth of 3D point cloud datasets have led to significantly higher training costs for 3D point cloud models in terms of both computation and memory bandwidth. Despite this, research on reducing this cost is relatively sparse. This paper identifies inefficiencies of unique operations in the 3D point cloud training pipeline: farthest point sampling (FPS) and forward and backward aggregation passes. To address the inefficiencies, we propose novel training optimizations that reduce redundant computation and memory accesses resulting from the operations. Firstly, we introduce Lightweight FPS (L-FPS), which employs progressive near point filtering to eliminate the redundant distance calculations inherent in the original farthest point sampling. Secondly, we introduce the fused aggregation technique, which utilizes kernel fusion to reduce redundant memory accesses during the forward and backward aggregation passes. We apply these techniques to state-of-the-art PointNet-based models and evaluate their performance on NVIDIA RTX 3090 GPU. Our experimental results demonstrate 2.25x training time reduction on average with no accuracy drop.