DNS performance question

[Albert Yeghikian]

Hi there;
I have many domains all using the same file  like this:

zone "X1.com" {
            type master;
            file " samefile"
};

zone "X2.com" {
            type master;
            file " samefile"
};

........

zone "Xn.com" {
            type master;
            file " samefile"
};

1- Is there any way to make it short in named.conf instead of the above
?
2- will it  affect the efficiency also to make  the named.conf as short
as possible  specially when transferring data to secondaries?

Thanks
Albert