There is an irony here that this would be more performant with a 2002 coding model. A native plugin, COM, OLE, whatever. C++, crash prone, but fast.

Maybe but not drastically so. My guess is that most of the slowness comes from the tool calls round tripping+processing on Anthropic/OpenAI’s servers rather than the app latency.

That’s without talking about the poor UI and security story of COM add-ins and the inability to run on Excel for iOS.