As much as we would like to, the iPad GPU (graphical processing unit) cannot handle the sheer complexity of a photo-real render. So we are using a super fast cutting edge server farm of hundreds of the best GPUs money can buy. We do not own this server farm and these behemoths are expensive.
We are looking into ways of sponsoring the cloud renders so users will not need to pay for them. In the meantime, we have to cover out-of-pocket costs for the servers performing the renders.
With that said, TapGlance has a local, non-photorealistic render mode, which is free. We are certain many users will find it more than suitable for their needs. You are welcome to try the local render first and decide if you actually need the extreme realism of a photo-real render.