64-bit App Support for WebAssembly

What is the benefit? Why is this valuable?
Most new machines are using 64-bit architecture and the 4 GB max memory space for an app limitation is not present in practice.
What are common use cases?
All wasm use cases.
Technical information
Browser support is to be clarified as well as runtime performance. Potential performance optimisation aspects to be clarified also. Qt already supports 64-bit so this task is somewhat straightforward.

Standards work:
https://github.com/WebAssembly/memory64
From there:
For many applications, 4 gibibytes of memory is enough. Using 32-bit memory indexes is sufficient in this case, and has the additional benefit that pointers in the producer language are smaller, which can yield memory savings. However, for applications that need more memory than this, there are no easy workarounds given the current WebAssembly feature set. Allowing the WebAssembly module to choose between 32-bit and 64-bit memory indexes addresses both concerns.

Integers and floating point numbers can already be 32 or 64-bit.