Steam is a popular gaming app known to use a lot of memory. However, there is a good workaround for that problem, with which you can reduce RAM usage from 400MB to around 60MB by cutting down some of its features.
The biggest Steam feature that is possible to cut down is WebHelper, which implements a web browser into the system and is required for Store to work.
To open Steam without WebHelper, you need to press Windows key + R, press the Run button and then copy-paste the following command:
"C:\Program Files (x86)\Steam\steam.exe" -no-browser +open steam://open/minigameslist
Remember, that you need to make sure that Steam is located at this path: "C:\Program Files (x86)\Steam\steam.exe" for this command to work!