I am not a mac expert, so this guide is written by a laymen for laymen. I will happily edit if experts have better methods or advice. I currently own my 2nd macbook pro which is a 2010 2.4ghz i5. When i purchased it initially, it would boot in about 30 seconds and shutdown nearly instantly. After installing programs and about 1 months use the bootup had doubled to a consistent 1 minute 7 seconds, and the shutdown was taking 20 seconds or even more. Even my old 2007 model booted and shut faster than this, so i knew something was not working. I cannot guarantee a fix for all, but i have pinned down what was certainly affecting my machine. Follow these steps if you are having problems - 1 - check system preferences > startup disk and make sure mac HD is highlighted. This will make your system boot from here 1st (this is a problem for most people), reboot and check your times again. This may be the simple cause... if not 2 - go to disk utility and scan and repair all permissions. Reboot and check times... fixed? 3 - download Onyx, use their SMART scan, repair permissions, and also go to clean, and tick 'kernel' and have it clear all the caches. Reboot, time it...fixed? if not, its probably this 4 - (what i had to do) go to applications > utilities > console and read through your last boot up log (under console messages). If in doubt about what to read here - check the time on your taskbar and shutdown at a round number like 5.30pm for example. This makes it easier to spot in your log, since all the times will then log events after this point. Study the logs for any error messages, not founds, or anything suspicious. Also check the 'system' log on the left hand pane. The problem i had was specifically the message in system log reading - CAN'T CREATE KEXT CACHE UNDER / - OWNER NOT ROOT. This i have learned is the result of a 3rd party program (possibly steam from what other people suspect) taking admin permission from you and altering system files incorrectly. The fix for this problem is to open up terminal (backup if you are in doubt!) And type the line - sudo chown root:admin / It then asks for your password, which you type (the letters will not show! but it is typing) and press enter. The process seemed almost instant, but i gave it 10 seconds anyway before closing and rebooting. This will correct the permissions, which some other program has chewed up and hopefully see your mac now running smooth during both startup and shutdown operations. I went from the above times (1:07 and 20 seconds) to 43 seconds boot and 1-2 seconds for shut down. I hope this helps people!