I am seeing the same issue here. When I use the 30-day trial everything went perfectly. That's why I decided to purchase the lightroom 5. I tried to purchase one with a serial number but that was not an option. So I went with the Creative Cloud one. And the problem immediately arose. Whenever I use Lightroom 5 my whole computer slowed down. The PS Element is extremely slow, the internet browser is very slow....
What is the cause? What is the solution? This hugely impacted my work efficiency.