On Sunday, 9 February 2014 at 16:12:30 UTC, Jakob Ovrum wrote:
> On Sunday, 9 February 2014 at 16:07:52 UTC, Marc Schütz wrote:
>> But the difference actual difference is so much larger. Where does it come from? It might mean that there is some costly operation that both `new` and `toString()` perform. Or it might actually be a bug, and when fixed, would have worse performance. It seems almost too good to be true...
>
> They both allocate GC memory, which can cause a collection cycle. Could that be it?

No, I just checked this by allocating another exception in addition to the one being thrown, and it made no difference.

But I think I've found the explanation, see my previous post.

> The results:
>
>                          A) vibe.d 0.7.17      B) vibe.d patched
> 1) no exceptions              13000 req/s          13000 req/s
> 2) dynamic exceptions           200 req/s            800 req/s
> 3) static exceptions            320 req/s          19000 req/s

New numbers with DMD/Druntime/Phobos git (includes the patch by Adam Ruppe):

                         A) vibe.d 0.7.17      B) vibe.d patched
1) no exceptions              15000 req/s          16000 req/s
2) dynamic exceptions           120 req/s          19000 req/s
3) static exceptions            120 req/s          19000 req/s

Dynamic and static exceptions are now equally fast, provided `toString()` is not called on them.