I doubt its the GC kicking in, but you could run it with the following environment variable set just to ensure that its not doing anything. GOGC=-1 EDIT:

I doubt its the GC kicking in, but you could run it with the following environment variable set just to ensure that its not doing anything. GOGC=-1 EDIT: Trying it out quickly shows a small improvement actually, but so small as to likely be noise as I was doing other things on the machine. Summary ./mainnogc 1000 ran 1.01 ± 0.06 times faster than ./maingc 1000