Developer Diary | Performance

Bonjour à nouveau, friends! I don’t know if the third time makes it a tradition but I appear once more before release to give some updates from HoI’s tech team.

If you haven’t seen much of me since last year, it’s because I’ve partly been busy with ** REDACTED **, ** REDACTED ** and also with ** REDACTED **, but my attention has fully returned to HoI for the last couple months.

So, what’s new with HoI’s tech in 1.13 “Stella Polaris”?

Mines, or the greatest urban legend

First off, great news, naval mines will not slow down the game anymore! Hurray!

Except that’s a lie. The “mine lag” I keep reading about in some community house rules isn’t a thing. Hasn’t been for 2 years. I know because I fixed it in 1.11 (Barbarossa). But don’t feel bad for missing the notice, as it turns out this change from December 2020 (shipped in 2021 with No Step Back) never ended up in the changelog.

commit da0ce4ac94ba1938459ffb6abe3bf2b0cd4bab1e Author: Mathieu Ropert Date: Mon Dec 14, 17: 38:59 2020 +0100 [X] Fixed performance issue when mines are used

Oops.

But I have even better news. While the usage of mines didn’t slow the game down, the existence of mines as a concept was still incurring a performance cost, whether you used them or not. This has also been greatly improved for 1.13.

So go ahead. Go nuts. Mine the whole ocean. See what happens.

V-Sync, G-Sync, Free-Sync, NSync…

While there is no big platform update this time (supported operating systems remain the same), we have introduced some small improvements to rendering tech in HoI.

The main one is support for variable refresh rate monitors and GPUs. If you use DX11 (the default since 1.12) and your hardware supports it (and you use Windows 10 or higher), you should get more FPS with vsync off. On my NVIDIA RTX 3060 at work, it goes up from 140-150 FPS in 1.12 to about 190 FPS in 1.13 when the game is paused.

I’m not saying you’ll actually be visually able to tell the difference, but you wouldn’t be our fans if you didn’t like when numbers go up, so this should give you some stonks for free.

We’ve also tweaked a bit how the game renders when unpaused, especially when your hourly/daily tick starts getting slower than 16/33/50ms (depending on game speed). Long story short, the “cost” of keeping the FPS going steady when the simulation gets more CPU heavy has been improved, meaning better FPS and less perceived “lag” especially in speed 4 and 5.

General performance improvements

I used the mines example earlier as a teaser, but in general this update comes with a good amount of performance improvements. Those were partly inspired by having spent time looking at our other titles and a bunch of secret stuff I sadly cannot delve into, and partly just due to getting a fresh set of eyes on old problems.

Here’s some side by side comparison between 1.12 (Avalanche) and 1.13 (Stella Polaris).

First, a fresh new 1936 game on my work i7-12700k and it’s 20 cores: HOI4 1.12 “Avalanche” - 1936 - Intel i7-12700k

HOI4 1.13 “Stella Polaris” - 1936 - Intel i7-12700k

And here’s 2 similar-ish saves from 1943, same machine: HOI4 1.12 “Avalanche” - 1943 - Intel i7-12700k

HOI4 1.13 “Stella Polaris” - 1943 - Intel i7-12700k

This might look a tad overwhelming if you’ve never seen the in-game profiler from previous dev diaries (console command imgui show profiler to make it pop in game). The bits I