How to time the execution of a method?

I'm thinking of doing a game remake, and I've reduced the 60 screens
of the game from the original 256x192 bitmaps to a compressed
bytestream using a two-pass process, first shrinking each screen to
32x24 tiles and then collapsing the result further using RLE. The
remake will use a 512x384 screen.

The problem is that I have three possible algorithms to re-inflate the
screen, and I want to know which is the most efficient on average.
I've tried using the following:

function TimeMethod(x: TMethod): TDateTime;
var s,e: TDateTime;
begin
s:=Now;
x;
e:=Now;
TimeMethod:=86400*(e-s);
end;


ta:=TimeMethod(DrawA);
tb:=TimeMethod(DrawB);
tc:=TimeMethod(DrawC);



This doesn't work. Please advise.
.