&gt;Excel alone uses 86.1MB of private memory, and 142MB on a Blank Workbook.<p>That is excel. With all its features. 100MB is Electron&#x27;s <i>base</i> footprint. Running absolutely nothing. Write something as complex as excel with the same feature set, you&#x27;re going to be way over 142MB with a blank workbook ;)<p>The 100MB metric comes from experimentation with both electron and electron based apps (VS Code, Atom, N1, Slack, ...). The main process hovers at around 80MB, but you also have countless node processes running. When node will be a default on machines (please, never), I&#x27;ll stop adding those processes to the total, but meanwhile, they do count.<p>&gt;I doubt it. Creating performant HTML layouts and WebGL rendering all verified by independent 3rd party test suites is hard, dude. If someone came to you and said &quot;Build a HTML engine or build Word&quot; which would you choose?<p>A) The electron developers do not develop a rendering engine. They do not develop a JS VM either. They develop a toolkit for desktop apps, which uses nodejs (which is highly dependent on Google not pulling the plug on V8) as well as Blink (which is highly dependent on Google). While I am not discounting their work, they are absolutely not the ones with their hands in the engine internals.<p>B) I would honestly build a rendering engine. Word has 25 years of backwards compatibility to keep, features and integrations with lots of other office software, etc. Rendering engines have a clear and defined spec. Microsoft hasn&#x27;t clearly defined the DOCX spec (well, they did, but keep adding undocumented surprises. Just like XLS :^).<p>C) I&#x27;d ask for a team, because no single human being can replicate the feature set of either in his lifetime.<p>Add-ins in JS? Sure, run them in an another thread and keep them out of performant code and we&#x27;ll be friends.