You can also manually optimize vector files before uploading them to a website. Using a vector editing software like Adobe Illustrator, you can delete any unused groups and layers in the file and simplify shapes by removing any unnecessary anchor points on paths. SVGs can also be edited in a code editor, albeit without the visual user interface. If there's anything you can delete without making any noticeable difference to the appearance of the image, then you have an opportunity to make the file smaller. On our team, we found that if we do manual optimizations first and then compress the SVG file using a tool like ImageOptim, we can reduce the size of vector files by up to 85 percent without anyone noticing.

— Sustainable Web Design by Tom Greenwood (Page 45)