OS X Lion slow bootup and shut down?

hello i have os x lion, i installed it on my late 2009 imac 27", i had snow leopard before. Ive noticed, that there is a BIG difference with lion bootup and shut down. Please help me, before it took it.. 30 sec to boot up completly and now it takes a stunning 1minute and 30seconds, and the shut down, before it took about 3 sec, and now like 10 sec. help please, this is very annoying.