The best laypersons's summary I could find:

"SLIDE doesn’t need GPUs because it takes a fundamentally different approach to deep learning. The standard “back-propagation” training technique for deep neural networks requires matrix multiplication, an ideal workload for GPUs. With SLIDE, Shrivastava, Chen and Medini turned neural network training into a search problem that could instead be solved with hash tables"

https://insidehpc.com/2020/03/slide-algorithm-for-training-d...