Memory usage isn't well understood. If you are using Activity Monitor on OSX the memory tab doesn't tell you much. Double click the process and look at the "Real memory size". That's a much more accurate picture of the physical ram being used by the process. It is typically much less than what you see on the memory tab overview.
tbh even that is inaccurate because Chromium uses shared memory heavily. The most real'est way to see is to note the total free memory, close the app, then subtract.
