Difference Between FindAll, FindChild, FindAllChildren ?

I have  a situation here. Im Creating function by finding the objects using any of the find method. I'm going to use the functions across all the project or webpages. So the find performs as per the DEPTH used. It changes changes and  the function fails. If I use a depth of huge number as 1000 or more, it finds it. But the execution is very slow.





Please help me how to resolve it??