a question about code speed of flex

What exactly are you demonstrating?  What I see is that evaluating one compound expression instead of two simpler expressions is about 12 times slower.  Of course, the actual delta is measured in fractional microseconds, so it's most likely due to slight variations in your CPU load at the time of the test, or perhaps the AS VM performing optimizations part way through the first loop.  Did you try the tests in reverse order?  In any case, the difference is WAY too small to care about in pretty much every situation. cheers, barneyb > > CODE 1 > > function test():void{ >        var loop:int = 0; > var i:int = 0; > var j:int = 0; > var now:Date = new Date(); > var d:Number = 1.1; > for(i=0;i<10;i++){ > for(j=0;j<10000000;j++){ > >  (d*=1.0000001)>1; > } > now = new Date(); > > text.text+=(""+now.getTime()+" "+d+"\n"); > } > } > > CODE 2 > > function test():void{ > > var loop:int = 0; > var i:int = 0; > var j:int = 0; > var now:Date = new Date(); > var d:Number = 1.1; > for(i=0;i<10;i++){ > for(j=0;j<10000000&&(d*=1.0000001)>1;j++){ > > > } > now = new Date(); > > text.text+=(""+now.getTime()+" "+d+"\n"); > } > } > > RESULT > 1 > 1265207560811 2.9901098635452765 > 1265207562139 8.127960905517952 > 1265207563374 22.094087340094895 > 1265207564593 60.05795316514031 > 1265207565764 163.25443467583585 > 1265207567061 443.7715412652174 > 1265207568389 1206.2960569981067 > 1265207569624 3279.052489441804 > 1265207570921 8913.38835614975 > 1265207572124 24229.100401210693 > > 2 > 1265207634858 2.9901098635452765 > 1265207634968 8.127960905517952 > 1265207635077 22.094087340094895 > 1265207635171 60.05795316514031 > 1265207635280 163.25443467583585 > 1265207635374 443.7715412652174 > 1265207635483 1206.2960569981067 > 1265207635577 3279.052489441804 > 1265207635686 8913.38835614975 > 1265207635780 24229.100401210693 > > Do anyone know what's the cause. > > >