[Solved] Boxing and Performance [closed]

Question

Boxing is considered slow because it implies the allocation of an object. In your case that object is short lived (will probably not survive Gen0), which makes it cheap. A recent microbenchmark I did put the cost of generating a short lived object at about ~15 CPU cycles. Cost might be a bit higher in real applications, but that boxing isn’t that expensive.

You should avoid allocations in performance critical code. But that means code that’s called >10 million times per second.

If you benchmark your above code, you’ll see that Console.WriteLine is the expensive part, and that optimizing out those two boxes has negligible impact.

When optimizing a program’s performance, I’d:

Profile to identify the bottleneck. But 99% of the code performance isn’t an issue
Rewrite it to your hopefully better version
Profile it again, and verify that the performance improvement is significant. If it is not, revert to the simpler code, or try another variation.

Accepted Answer

Boxing is considered slow because it implies the allocation of an object. In your case that object is short lived (will probably not survive Gen0), which makes it cheap. A recent microbenchmark I did put the cost of generating a short lived object at about ~15 CPU cycles. Cost might be a bit higher in real applications, but that boxing isn’t that expensive.

You should avoid allocations in performance critical code. But that means code that’s called >10 million times per second.

If you benchmark your above code, you’ll see that Console.WriteLine is the expensive part, and that optimizing out those two boxes has negligible impact.

When optimizing a program’s performance, I’d:

Profile to identify the bottleneck. But 99% of the code performance isn’t an issue
Rewrite it to your hopefully better version
Profile it again, and verify that the performance improvement is significant. If it is not, revert to the simpler code, or try another variation.