Potential optimizations

[lidavidm]

• clearRect
• Separate canvas or CSS background
• Separate canvas for infrequently drawn items (toolbox bg, goal, sidebar)
• Smaller canvas with scaling (piecewise linear: 1x scaling to max of 1.5x scaling; beyond that don't scale further)
• https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Optimizing_canvas
• https://developer.mozilla.org/en-US/docs/Web/API/Path2D/Path2D (benchmark - hopefully would speed up certain ops?)
• https://www.html5rocks.com/en/tutorials/canvas/performance/
• Pre-rendering and mip-mapping text?
• Using image decal?

[lidavidm]

https://developers.google.com/web/updates/2018/04/nic66#css-paint-api might help when drawing lots of sprites