The System monitor says that a process named zeitgeist takes up about 450 MB of memory

Question

Is that normal? What happens if I uninstall it?

Answer 1

To be short, you can uninstall it and be fine.

Zeitgeist doesn’t log everything; it can only log what we, or an app we use, tells it to. We can even switch it off completely.

It logs data apps, or the user send to it, and the data is used by apps that request it, most notably, the dash, to provide better results. And yes, that amount of memory usage is fairly normal.