Hacker News Reader

Comment by geokon | Hacker News Reader

Just curious - is this from personal experience?

I've never done it, but I just find it hard to believe the slow down would be that large. Most of the computation is on GPU, and you can set your build up such that you link to libraries built at different compilation optimizations.. and they're likely the ones doing most of the heavy lifting. You're not rebuilding all of the underlying libs b/c you're not typically debugging them.

EDIT:

if you're targeting a console.. why would you not debug using higher end hardware? If anything it's an argument in favor of running on an interpreter with a very high end computer for the majority of development..

View on HN

Yeah, around 3x slower is what I've seen when I was still working on reasonably big (around a million lines of 'orthodox C++' code) PC games until around 2020 with MSVC and without stdlib usage.

This was building the entire game code with the same build options though, we didn't bother to build parts of the code in release mode and parts in debug mode, since debug performance was fast enough for the game to still run in realtime. We also didn't use a big integrated engine like UE, only some specialized middleware libraries that were integrated into the build as source code.

We did spend quite some effort to keep both build time and debug performance under control. The few cases were debug performance became unacceptable were usually caused by 'accidentially exponential' problems.

> Most of the computation is on GPU

Not in our case, the GPU was only used for rendering. All game logic was running on the CPU. IIRC the biggest chunk was pathfinding and visibility/collision/hit checks (e.g. all sorts of NxM situations in the lower levels of the mob AI).

Ah okay, then that makes sense. It really depends on your build system. My natural inclination would be to not have a pathfinding system in DEBUG unless I was actively working on it. But it's not always very easy to set things up to be that way

The slowdown can be enormous if you use SIMD, I believe MSVC emits a write to memory after every single SIMD op in debug, thus the code is incredibly slow(more than 10x). If you have any SIMD kernels you will suffer, and likely switch to release, with manual markings used to disable optimizations per function/file.

I was working on a 2d game in Rust, and no joke the debug build was 10x slower than release.

Reply on news.ycombinator.com