Test the ram and ensure it's running stable AND at the same speed you were using it at before. It's possible that you damaged it in some subtle way. You can run a program like memtest to check the ram. If you ram runs without any errors and is definitely running at the same speed as before, then, assuming you did not touch any other components while removing the ram, perhaps it is just coincidence?
Also, did you install anything before turning your computer off? Or install any updates to anything? Does your computer constantly take that long? If it functions fine but loads slowly, you should run hardware tests (such as the aforementioned memory test) and software tests - boot from a live cd and run a virus scan, run an antirootkit tool, etc.