A logo or a name for laser engraving should fit in a small SVG. When the file weighs several megabytes, it is slow to open, it may be refused by an upload form with a size limit, and the weight is almost always something the laser does not need. Here is how to find what makes an SVG heavy and how to slim it down without changing the design.
Open the SVG in a plain text editor and search for <image and base64. A long block of random-looking characters after data:image/png;base64, or data:image/jpeg;base64, is a bitmap stored inside the SVG, and it is usually most of the file size. If there is no image, look for paths with very long d="..." attributes: that is usually a traced bitmap with thousands of nodes.
A photo or screenshot pasted into the design is still a bitmap: it cannot be cut, and it makes the SVG heavy. Delete images that were only used as a reference for drawing. If you need its outline as a cut line, trace it to vectors (Inkscape Path > Trace Bitmap, Illustrator Image Trace) and delete the original image. For photo engraving, ask the shop how it wants the photo, often as a separate file.
Traced outlines often contain far more nodes than the laser needs. Select the path and use Inkscape Path > Simplify (Ctrl+L) or Illustrator Object > Path > Simplify, then compare with the original at 100% zoom. When tracing, the smoothing and speckle options reduce noise before it becomes nodes.
Unlock and show all layers, delete what is hidden or outside the page, then run Inkscape File > Clean Up Document to remove unused gradients, patterns, markers and other definitions.
Inkscape SVG keeps editor data. File > Save a Copy as Plain SVG removes it, and Optimized SVG also shortens numbers, merges styles and removes metadata and comments. In Illustrator, File > Export > Export As > SVG offers a decimal precision setting and a Minify option. Keep a copy of the editable original.
Coordinates with 8 decimals add size without adding accuracy for a laser. Two or three decimals in millimetres are generally enough, but check small text and fine details after the change, because too few digits can distort tiny shapes. Command-line users can do the same with the open-source tool SVGO.
A gzip-compressed .svgz is smaller, but it is a different file type, and many upload forms, including CutReady, accept only .svg, .dxf and .pdf.
Look at the file size in your file manager, reopen the SVG, and confirm that the size and units are still right (see the SVG requirements guide), that text is still outlined, and that cut lines are closed.
If you sell laser or CNC work on Shopify and customers upload their own files, CutReady checks the file on the product page before add-to-cart. It accepts only .dxf, .svg and .pdf, with size limits of 256 KB for SVG, 512 KB for ASCII DXF (binary DXF is not accepted) and 2 MiB for PDF, and add to cart stays locked until the file passes ("File OK"). Free trial, then 39 USD every 30 days, billed by Shopify. The app is awaiting Shopify App Store review.