Maybe; maybe not. Regardless, they aren't in a position to alter their software to the degree required at this time.
Replacing a function with a faster implementation is trivial; its just another deployment and we do several of those each week. Changing data format adds operational complexity - two codepaths need to be run and maintained and we increase system load and lower response times for the duration. (The data format is versioned, so that's easy - no architectural problem there).
Its totally worth doing if you need to, and we're not afraid of that, but you don't do it on a whim - it takes proper planning and testing and needs multiple people involved.