Add stateless doc, prefer stateless mode and disable legacy SSE by default #2549

Job	Run time
build (macos-latest, Release)	4m 53s
build (ubuntu-latest, Release)	7m 11s
build (windows-latest, Debug)	11m 15s
build (ubuntu-latest, Debug)	13m 25s
build (macos-latest, Debug)	6m 29s
build (windows-latest, Release)	11m 58s
publish-coverage	0s
	55m 11s

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