that calculator took 35 seconds to load on my ipad pro... not a great first impression (and the ui lag was quite noticable as well)
The Safari Support for large WebAssembly binaries is not particularly great at this point. We hope that the Safari team will improve the performance aspects of WebAssembly, but it does not seem to be a priority at this point (see the Wasm feature map here: https://webassembly.org/roadmap).
For the iPad, the iOS built version of the same app works lots better (https://apps.apple.com/us/app/uno-calculator/id1464736591).