list_bench.vim

let list = []
echo 'call add(list, i)'
let time = reltime()

for i in range(10000)
  call add(list, i)
endfor

echo reltimestr(reltime(time))

let list = []
echo 'let list += [i]'
let time = reltime()

for i in range(10000)
  let list += [i]
endfor

echo reltimestr(reltime(time))

let list = []
echo 'let list = list + [i]'
let time = reltime()

for i in range(10000)
  let list = list + [i]
endfor

echo reltimestr(reltime(time))



let list = []
echo 'call insert(list, i)'
let time = reltime()

for i in range(10000)
  call insert(list, i)
endfor

echo reltimestr(reltime(time))

let list = []
echo 'let list = [i] + list'
let time = reltime()

for i in range(10000)
  let list = [i] + list
endfor

echo reltimestr(reltime(time))

finish

=> result (Intel Core2 2.40GHz + 2.00GB RAM)
call add(list, i)
  0.066588
let list += [i]
  0.070910
let list = list + [i]
 14.713714
call insert(list, i)
  0.069628
let list = [i] + list
 15.083124