I think the only limit will be our patience and computer memory. For example, the following is the timing on my OS 10.4 iBook.
Clear["Global`*"];
m[n_]:= Table[{RandomInteger[{0,9}],RandomInteger[{0,9}],{i,1,n}];
#[[1]]& /@ {Timing[m[#];]& /@{10^1, 10^3, 10^3} }
(* Output in seconds *)
0.00024, 0.0031, 1.88
