Quick edits should not need a heavyweight app. Change a cell, tweak a vector or write some Markdown and download the result.
Open a file, make your changes and save it back in the same format. The editors focus on the common operations, so they load fast and stay easy to use even on a modest laptop.
Work happens in your browser tab, so closing it before you download loses unsaved changes. Keep a copy of the original file, especially before bulk edits such as find and replace across a whole sheet.
The CSV editor and Excel viewer-editor cover tabular data and formulas, the SVG editor is suited to tweaking paths, colors and icons without a full design app, and the Markdown editor is the fastest path from a quick note to a formatted README or blog draft.