I updated my iMac to 10.9.1 Mavericks today. I had to update a graphics converter called Flip4Mac that plays Windows video files on Macs. It looks like Adobe Lightroom is running a little slower on the new OS. I’ve read that Mavericks likes more memory, I have 24 GB installed so I should be fine. Earlier I installed it on my older Mac Pro laptop, where the speed decline was noticeable. This 6 year old laptop is maxed out at 4GB of memory and has 2 cores vs. the 4 in the iMac.
I had no problems with the hour long update. Prior to installing I used disk utility to make sure there were no problems with the hard drive, and I also told it to fix file permissions and it fixed quite a few files. I had read to do this before updating the OS. Cost to update from 10.8? $0.00 Nice, thanks Apple. How much does Microsoft charge for a major OS update?