I had this exact same "we take our coffee break while this is loading" experience. However it wasn't our code and we ended up fixing it, for free to the client

I had this exact same "we take our coffee break while this is loading" experience. However it wasn't our code and we ended up fixing it, for free to the client and actually at a non-insignificant expense to us, because we wanted to show the client that we were better then the previous vendor in hopes of winning more of their business down the line (which we did). So if you don't fix it you leave yourself open to competition.