Will do / have done:

• Serve images in next-gen formats (.webp)
• Buttons do not have an accessible name
• [user-scalable="no"] is used in the element or the [maximum-scale] attribute is less than 5
• Ensure text remains visible during webfont load (by using font-display: swap;)

Won't/can't do:

• Serve static assets with an efficient cache policy (long cache lifetime) PWA-wise cache with reasonably long lifetime is set
• Avoid enormous network payloads [already minified] more optimizations done in 2025
• Some elements have a [tabindex] value greater than 0 [by design] fixed anyway

Edit: Did a lot of optimizations, including code and performance-wise optimization, and image polishing in early 2025 (changelog) and v2.0.0 is available now!