Matching pair of numbers {a,-a}, where a is numeric

lst = {{2, -2}, {1, 5}, {1, -3}, {-3, 3}};
Pick[lst, Total[lst, {2}], 0]

{{2,-2}, {-3,3}}

First @ Timing[res0 = Pick[Ta, Total[Ta, {2}], 0];]

0.093750

First @ Timing[res0a = Pick[Ta, Total /@ Ta, 0];]

0.187500

First @ Timing[res0b = Pick[Ta, Plus @@ Transpose[Ta], 0];] (*thanks: 2012rcampion *)

0.062500

First @ Timing[res1 = DeleteCases[Ta, {a_, b_} /; a != -b];]

4.093750

First @ Timing[res2 = Cases[Ta, {a_, b_} /; a + b == 0];]

3.656250

Equal @@ {res0, res0a, res0b, res1, res2}

True

Update: for the case where a is any real number you can Unitize the selector array (thanks: @MrWizard):

First @ Timing[Pick[Ta, Unitize@Total[Ta, {2}], 0];]

0.125000

First @ Timing[Pick[Ta, Unitize[Total /@ Ta], 0];]

0.156250

First @ Timing[Pick[Ta, Unitize[Plus @@ Transpose[Ta]], 0];]

0.046875

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