Lowest latency of DDR5-6400 on normal PC starting at 60ns+
Lowest latency of VRAM on GeForce RTX 4090 starting at 14 ns
Lowest latency of Apple M1 Memory starting at 5 ns, its more like L3 cache
And on Apple M chip, this ultrafast memory is available for CPU, GPU and NPU.
https://www.anandtech.com/show/17024/apple-m1-max-performanc... https://chipsandcheese.com/p/microbenchmarking-nvidias-rtx-4...