Hi @Scott_Collier-Weir - That’s a great observation, and nice to see data to back it up! This difference in speed is due to how these different types of formulas are run. Pack formulas are run on a server, with each formula call being run on a separate server. There is an overhead for each call, sending the data over the network and getting the server warmed up, which is small in absolute terms but as you have found can add up. Coda native formulas are instead run in your browser, which has no such overhead and allows for a lot of calls to be processed in parallel.
I think in many cases the convenience and additional capabilities (pulling in external data) of Pack formulas is worth the tradeoff, but there are times when the speed matters and native Coda formulas will be the better choice for now. We’ve already started having some discussions about ways we can improve the speed of Pack formulas, but I wouldn’t expect any significant changes in the near term.