I love Okular. It’s a great alternative to that bloated, buggy pile of proprietary garbage known as Adobe Acrobat Reader. But it has a big appetite.
According to this old bug report, it’s not going to get fixed any time soon. I put it on a diet by going to:
and selecting ‘Low’ under ‘Memory Usage’. This reduced its resident memory footprint from >500MB to ~62MB!
Here’s a list of all open Okular bugs sorted newest first.