ATTiny13 -- avr-gcc Hello World uses over 100 bytes?
You can use avr-objdump -d .elf to see what's being generated:

Let's analyze it a little:

[jpc@jpc ~] avr-objdump -d avr.elf | sed -e 's/^/    /' | pbcopy

avr.elf:     file format elf32-avr

Disassembly of section .text:

00000000 &lt;__vectors&gt;:
   0:   09 c0           rjmp    .+18        ; 0x14 &lt;__ctors_end&gt;
   2:   0e c0           rjmp    .+28        ; 0x20 &lt;__bad_interrupt&gt;
   4:   0d c0           rjmp    .+26        ; 0x20 &lt;__bad_interrupt&gt;
   6:   0c c0           rjmp    .+24        ; 0x20 &lt;__bad_interrupt&gt;
   8:   0b c0           rjmp    .+22        ; 0x20 &lt;__bad_interrupt&gt;
   a:   0a c0           rjmp    .+20        ; 0x20 &lt;__bad_interrupt&gt;
   c:   09 c0           rjmp    .+18        ; 0x20 &lt;__bad_interrupt&gt;
   e:   08 c0           rjmp    .+16        ; 0x20 &lt;__bad_interrupt&gt;
  10:   07 c0           rjmp    .+14        ; 0x20 &lt;__bad_interrupt&gt;
  12:   06 c0           rjmp    .+12        ; 0x20 &lt;__bad_interrupt&gt;


20 bytes interrupt vector table (at least some of the entries could be omitted if you insisted and promised you would never enable the corresponding interrupts).

00000014 &lt;__ctors_end&gt;:
  14:   11 24           eor r1, r1
  16:   1f be           out 0x3f, r1    ; 63
  18:   cf e9           ldi r28, 0x9F   ; 159
  1a:   cd bf           out 0x3d, r28   ; 61
  1c:   02 d0           rcall   .+4         ; 0x22 &lt;main&gt;
  1e:   05 c0           rjmp    .+10        ; 0x2a &lt;_exit&gt;


Clears SREG (I am not sure this is really needed), writes 0x9f (RAMEND) to SPL (the stack pointer) and jumps to main. The last rjmp is kind of redundant. (you could promise never to return from main)

00000020 &lt;__bad_interrupt&gt;:
  20:   ef cf           rjmp    .-34        ; 0x0 &lt;__vectors&gt;


Default interrupt procedure for those interrupts than do not have one overwritten in C. (same rules as for __vectors)

00000022 &lt;main&gt;:
  22:   bb 9a           sbi 0x17, 3 ; 23
  24:   c3 9a           sbi 0x18, 3 ; 24
  26:   c3 98           cbi 0x18, 3 ; 24
  28:   fd cf           rjmp    .-6         ; 0x24 &lt;main+0x2&gt;


Your main proc. Tight.

0000002a &lt;_exit&gt;:
  2a:   f8 94           cli

0000002c &lt;__stop_program&gt;:
  2c:   ff cf           rjmp    .-2         ; 0x2c &lt;__stop_program&gt;


This two are not very useful. _exit is probably required by the C standard and __stop_program is needed for it to work as it should.