That depends on the amount of RAM you have. The less you have, the more limits are put in place per program. I have 4 GB of RAM, and I barely reach 50% now, besides when running FL Studio. If your CPU runs 36% by default, and has an increase of 13% when using DS, that suggests you aren't using a pretty new computer. That's why we need statistics, to know for sure.
The lifespan of your computer will not likely decrease that much, however, the older the computer, the more it will. But I wouldn't worry about that, since most computers have a lifespan longer than the time it takes until it gets replaced by something newer.
