#D, 130 bytes

import std.stdio,std.conv;void main(){string x;for(int i;i++<100;x=((i%3?"":"Fizz")~(i%5?"":"Buzz")),writeln(x?x:i.to!string)){};}

Ungolfed:

module FizzBuzz;
import std.stdio;
import std.conv;
void main() {
 string x;
 for (
 int i;
 i++ < 100;
 x = ((i % 3 ? "" : "Fizz")
 ~ (i % 5 ? "" : "Buzz")),
 writeln(x ? x : i.to!string)
 ){};
}

Or, building a string, for 142 bytes,

import std.stdio,std.conv;void main(){string x,y;for(int i;i++<100;x=((i%3?"":"Fizz")~(i%5?"":"Buzz")),y~=(x?x:i.to!string)~"\n"){};write(y);}

Ungolfed:

module FizzBuzz;
import std.stdio;
import std.conv;
void main() {
 string x,y;
 for (
 int i;
 i++ < 100;
 x = ((i % 3 ? "" : "Fizz")
 ~ (i % 5 ? "" : "Buzz")),
 y ~= (x ? x : i.to!string) ~ "\n"
 ){};
 write(y);
}

D, 130 bytes

import std.stdio,std.conv;void main(){string x;for(int i;i++<100;x=((i%3?"":"Fizz")~(i%5?"":"Buzz")),writeln(x?x:i.to!string)){};}

Ungolfed:

module FizzBuzz;
import std.stdio;
import std.conv;
void main() {
 string x;
 for (
 int i;
 i++ < 100;
 x = ((i % 3 ? "" : "Fizz")
 ~ (i % 5 ? "" : "Buzz")),
 writeln(x ? x : i.to!string)
 ){};
}

Or, building a string, for 142 bytes,

import std.stdio,std.conv;void main(){string x,y;for(int i;i++<100;x=((i%3?"":"Fizz")~(i%5?"":"Buzz")),y~=(x?x:i.to!string)~"\n"){};write(y);}

Ungolfed:

module FizzBuzz;
import std.stdio;
import std.conv;
void main() {
 string x,y;
 for (
 int i;
 i++ < 100;
 x = ((i % 3 ? "" : "Fizz")
 ~ (i % 5 ? "" : "Buzz")),
 y ~= (x ? x : i.to!string) ~ "\n"
 ){};
 write(y);
}