What did you expect to see?
Compilation times that would be less than 2x those of 1.4.2.

Unfortunately this won't be true for go 1.5. From the release notes:

Builds in Go 1.5 will be slower by a factor of about two.

So the slowdown you are seeing is expected.

@ALTree I’m not good with math, but 12.39 seems like way more than double 4.66. And the CPU usage! I’m worried about my battery life!

@aviflax 2x is not a hard and fast number. If you were experiencing a 20x slowdown, this would be more pressing, but 2.65x is not dramatically out of range. (And yes, the slowdown is very unfortunate. I am not happy about it either.) All that said, is your program available somewhere? I doubt that there is anything safe that could be done to address it at this point in the release cycle, but if we can reproduce it, that'll help with Go 1.6 speed-up efforts.

@josharian TBH, I figured. I still thought it might be helpful to report what I’m seeing. Unfortunately this is a private and proprietary program; I can’t share its source without at least an NDA and certainly not publicly. If it helps, according to cloc it has 121,123 lines of code (excluding comments and blanks) across 1,059 files. That’s including all vendored dependencies — as far as I can tell it excludes only the standard library. And I’m pretty sure all those files are included in compilation — we use Godep and I think it only includes the specific packages that our program actually uses.

Ok, thanks. The LOC count doesn't matter as much as what the actual lines are. :) If you want to poke at it more, you can run the compiler and linker with cpu and memory profiling enabled and share your findings in case there is anything usual. However, given the slowdown level you report, I'd guess that there's nothing peculiar to your code base. I'm going to close this for now. Feel free to reopen if you have significant new info.