dict is really slow for big truck

[forrest yang]

i try to load a big file into a dict, which is about 9,000,000 lines,
something like
1 2 3 4
2 2 3 4
3 4 5 6

code
for line in open(file)
   arr=line.strip().split('\t')
   dict[arr[0]]=arr

but, the dict is really slow as i load more data into the memory, by
the way the mac i use have 16G memory.
is this cased by the low performace for dict to extend memory or
something other reason.
is there any one can provide a better solution