There are currently two tabs opened in Nautilus. It has been running for quite a while, there have been more opened and closed before, and there have been switching between directories using bookmarks before. Now Nautilus takes up about 300MB memory shown in "Memory" column in system monitor. This happened quite often. I wonder if it is reasonable?
If I exit Nautilus, and restart it, and open just two tabs, the memory used is just 16.3MB.