Check if write caching is enabled on your hard disk (the one you boot from). If not, enable it and respond.
20 seconds to come out of hibernation (assuming you're including the bios post time) is quite normal. Roughly it would take you 10-15 seconds for the post to finish (from the time you switch on until the time you see the "Resuming from hibernation" message) and 5-10 seconds for coming out of hibernation. BTW, the less RAM you have, the less time it will need to hibernate and come out of hibernation.