Fast SSDs are still orders of magnitude slower than RAM access - SSD latency is on the order of 10s of microsecons, while RAM access latency is on the order of 10s of nanoseconds.
You're in luck because your working set happens to fit into RAM, and the rest is written to swap out gracefully and doesn't pull itself back into memory. But as soon as you're actually working with more than 16GB of data at once, you're in trouble.
You're in luck because your working set happens to fit into RAM, and the rest is written to swap out gracefully and doesn't pull itself back into memory. But as soon as you're actually working with more than 16GB of data at once, you're in trouble.