Well 21MB is small when you consider it to other applications, my anti-spam is running at 103Mb, thunderbird at 166MB, firefox at 511MB (and that is only one of its entries, dropbox at 50MB.
So it rather depends on your perspective of heavy, but RAM is their to be used as that improves performance so it isn't constantly swapping out to the hard drive pagefile.sys. For me the main thing would be CPU activity (nowadays RAM is cheap and plentiful) and that is negligible.