Using index of type INT in texture fetch

Is there any cast operation from int to float applied to the arguments of the texture fetch function in the kernel? For example:

int i=0;
tex2D(texture, i,i);

The question is whether “i” is cast to float here in execution time?

The reason for my question is that I noticed that texture fetches from the same address by all the threads in a block work slightly slower than similar constant memory fetches. Or maybe its just an artifact of something else.