LSL Script Efficiency
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What is Efficiency
Efficiency is how long it takes to run a script.
There are many ways to speed up scripts, such as using ++a instead of a++.
However most of those micro optimizations might not hold true in the future. But there are some common guidelines for things to avoid:
- set timers to insane short frequency (<5sec)
- listen - especially to the 0 channel
- changing textures on attachments (others have to download them)
- use of server/physical rotations instead of omega
- event handlers which are not needed (touch, collision, ...)
- large amount of email or IM
- inefficient algorithms (like linear search)
- busy (polling) loops
Rules for posting
1. Don't add theories.
2. Don't write "x is faster than y", write, "x takes X millis, y takes Y milis".
The following code will get the time for each function call in millis.
Please do not modify the script below, as any small change could change efficiency. Thanks to Strife Onizuka for optimizing the code.
//IMPORTANT: Only perform tests in an empty region to reduce contamination and be sure to wearing no attachments. integer time() { string stamp = llGetTimestamp(); return (integer) llGetSubString(stamp, 11, 12) * 3600000 + (integer) llGetSubString(stamp, 14, 15) * 60000 + llRound((float)llGetSubString(stamp, 17, -2) * 1000000.0)/1000; //llInsertString(llDeleteSubString(stamp, 19, 19) + "000000", 23, ".") } default { state_entry() { //test variables float counter; //framework variables float i = 0; float j = 0; float max = 10000; float start = time(); do { //test counter += 1; }while (++i < max); float delta = time(); do ; while (++j < max); float end = time();//remove the time required by the framework float t = ((delta - start) - (end - delta))/max; llOwnerSay("The function in the loop took a total of " + (string)t + " milliseconds."); } }
Efficiency
While the following data is correct, the function above was not used. A slightly less optimized version written by Xaviar Czervik was used. If someone could please repeat the tests with the function above.
In theory, ++a and a += 1 are equal in speed, however this is not true:
++a: 0.364700 millis a += 1: 0.346900 millis a++: 0.413700 millis
Testing the same function in for loops:
++a: 0.358370 millis a += 1: 0.351200 millis a++: 0.424600 millis
llOwnerSay v. llSay v. llShout v. llWhisper (Channel 0 where applies):
llOwnerSay(): 4.359000 millis llWhisper(): 5.201000 millis llSay(): 5.226000 millis llShout(): 14.877000 millis
Different Channels (llSay() Used for all):
-100000000: 1.226400 millis -100000: 1.254300 millis -100: 1.296100 millis -1: 1.292400 millis 0: 5.226000 millis 1: 1.242300 millis 100: 1.249100 millis 100000: 1.219700 millis 100000000: 1.228700 millis
Amount of text (llSay() and Channel 1 used for all):
1 Character: 1.242300 millis 10 Characters: 1.309700 millis 100 Characters: 1.965600 millis