I want to develop something like Openelec or osmc for Raspberry pi. My understanding is that they are operating system optimised to run kodi. (please let me know if I am wrong). Please tell me where should I start? And how to optimise a Linux to run a specific application so that the application runs very fast on raspberry pi? Thanks in advance.
These applications doesn't *run* any particular faster than on a normal Raspbian distribution, but they do *start* sooner after boot because there is little else installed that need to start at the same time.
OpenElec is actually very extensible. It it easy to disable Kodi and run your application instead. There is nothing specific in OpenElec, that makes it dedicated to run Kodi, other than in it's default configuration it has all the components necessary to run Kodi.
You can change the os configuration to match your application requirements.