Howard Locker of Lenovo claims that “ThinkPad notebooks and ThinkCentre desktop PCs for businesses will boot Windows 7 up to 56% faster than when loading XP or Vista. And IdeaPad and IdeaCentre consumer PCs certified for "Windows 7 Lenovo Enhanced Experience" will load 33% faster and shutdown 50% faster than non-certified-but-otherwise-identical hardware.” Some specific things Lenovo did to fine-tune Windows 7:

• Fixed on-board hardware components drivers, causing massive delays, e.g. a "popular wireless device" had been re-written.
• Tweaked BIOS to temporarily hide some devices from Windows 7, so that the OS only loads the drivers after the boot is finished.
• Tweaked Windows 7 to delay loading of non-essential services and applications until after startup, include automatic-updating apps for Adobe and Microsoft, or even Windows features.
• Rewrote power manager to be easier to use.