Hey great eye. I generally design in Illustrator with a plugin by Astute graphics that allows me to reduce unnecessary anchor points, run the exported SVG through SVGOMG, and then spend solid time hand coding each background in VS Code with the SVG extension by Jock that let's me see a live preview. Then on the actual site the customizer script I wrote will catch some attributes that aren't needed and remove them, but it's far from perfect.