I'm having the same issue, even when I've code in place to check if a spawn already has been used that tick

I'm working on an automated construction planning script, but I'm constantly getting the error that I'm using too much cpu.

After some testing with the following code on the main server:

var start = Game.cpu.getUsed();
for( var i = 0; i < 5; i++) {
     Game.rooms['E13N21'].createFlag(10 + i,10 + i,null);
}
console.log("Cpu used " + (Game.cpu.getUsed() - start));

 I'm getting the following results:

[11:17:12 PM]Cpu used 139.773812

[11:17:16 PM]Cpu used 414.195368

[11:17:19 PM]Cpu used 180.817071

[11:17:21 PM]Cpu used 193.585359

[11:17:24 PM]Cpu used 165.31457400000002

[11:17:27 PM]Cpu used 200.04942400000002

[11:17:31 PM]Cpu used 193.477699

[11:17:34 PM]Cpu used 417.859175

[11:17:37 PM]Cpu used 196.759669

[11:17:40 PM]Cpu used 195.42644199999998

[11:17:42 PM]Cpu used 206.136035

[11:17:46 PM]Cpu used 182.28700999999998

[11:17:49 PM]Cpu used 229.220531

[11:17:52 PM]Cpu used 426.39616700000005

[11:17:56 PM]Cpu used 212.994109

[11:17:59 PM]Cpu used 205.381853

[11:18:02 PM]Cpu used 234.454314

[11:18:05 PM]Cpu used 278.907558

[11:18:08 PM]Cpu used 254.071182

[11:18:12 PM]Cpu used 297.75649300000003

[11:18:14 PM]Cpu used 303.071679