LSL Optimizations and Hacks

::I'd love to see this stickied::
ok the idea here is to post an optimization or a hack/workaround that you know and have PERSONALLY tested... don't just post it because someone said it's faster/better/whatever. tell if it's faster, uses less memory, and if it has a trade-off (for example, some things can be faster but use more memory, others can be slower, but use less)

if you want a way to test try here

and hey if you include test times, and sample used to test, even better

ok so here goes my (short) list

++a
--a
tested faster than
a++, a+=1, a=a+1
a--, a-=1, a=a-1

(list)"abc" //-- only works for single items
tested faster than
["abc"]

a
!a
tested faster than
a!=0
a==0

~a
!~a
tested faster than
a!=-1
a==-1

The "WarpPos(vector d)" user-made hack of llSetPos, pretty much. It breaks the 50m/s limit of llSetPos loop, and can pretty much move at almost "warp speed".

WarpPos( vector d ) //R&D by Keknehv Psaltery, ~05/25/2006
	   {
			     if ( d.z > 768 )      //Otherwise we'll get stuck hitting the ceiling
			 d.z = 768;
	   integer s = (integer)(llVecMag(d-llGetPos())/10)+1; //The number of jumps necessary
			     if ( s > 100 )  //Try and avoid stack/heap collisions with far away destinations
			         s = 100;    //  1km should be plenty
	 integer e = (integer)( llLog( s ) / llLog( 2 ) );   //Solve '2^n=s'        
	 list rules = [ PRIM_POSITION, d ];  //The start for the rules list
	     integer i;
			 for ( i = 0 ; i < e ; ++i )     //Start expanding the list
	 rules += rules;
	 integer r = s - (integer)llPow( 2, e );
			 if ( r > 0 )                    //Finish it up
	 rules += llList2List( rules, 0, r * 2 + 1 );
			 llSetPrimitiveParams( rules );
	 }
 

hmm maybe it would have caught on if I'd named it "Things you CAN do in LSL"



results obtained with

 	touch_start(integer total_number)
 	{
 		vgKeyOwner = llGetOwner();
 		do{
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			vgLstTest += (list)vgKeyOwner;
 			llOwnerSay( (string)llGetListLength( vgLstTest) );
 		}while (TRUE);
 	}
 

yielded 160 before stack/heap collision

vs

 	touch_start(integer total_number)
 	{
 		vgKeyOwner = llGetOwner();
 		do{
 			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
  			vgLstTest = (vgLstTest = []) + vgLstTest + (list)vgKeyOwner;
 			llOwnerSay( (string)llGetListLength( vgLstTest) );
 		}while (TRUE);
 	}
 

yielded 320 before stack/heap collision

note that the test of
vLstTest = llListReplaceList( vLStTest, [vKeyOwner, vKeyOwner], -1, -1 );

vs

vLstTest = (vLstTest = []) + llListReplaceList( vLStTest, [vKeyOwner, vKeyOwner], -1, -1 );

showed NO difference, both crashed after 151