What Murienn said. Plus, locking out the suspension takes care of the suspension absorbing some of your effort that should go into forward movement, but it's still heavy and it still needs regular maintenance which can be $100 or more dollars and is recommended every year. I stretch mine out to every 2 years but I like to live on the edge.
Living life like there's no tomorrow.
http://gorgebikefitter.com/
2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS