For the last two weeks some I'm finding some strange files in my domain one of them is core.30695 other files are also of same name but different code these files made my site very heavy and it takes lots of time to load nay page, I have changed my account info 5 times but no vain. Can some body help me what are these files and who is sending it to my domain?
Those files are crash logs (core dumps) and generated by your hosting. You can ask help to your hosting by mentioning those crash file pathes.
Those files are core dumps (an image of the server memory contents) of a certain process and they are generated by the server when an unresolvable error occurred in a (probably your) application.