# Cities: Skylines II Hotfix - Patch 1.5.8f1

- Product: Cities: Skylines II (https://whatsnew.fyi/product/cities-skylines-ii)
- Vendor: Iceflake Studios
- Date: 2026-05-05
- Original notes: https://store.steampowered.com/news/app/949230/view/666112377194808967
- Permalink: https://whatsnew.fyi/product/cities-skylines-ii/releases/2026-05-05-hotfix-patch-1.5.8f1

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Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **fixed** — Fixed long loading times when mods are loaded at startup
- **fixed** — Fixed a crash when loading a save game
- **changed** — Info and Warning level logging no longer print callstacks to log files

**Hello Mayors!**

_This patch should not affect mods, and loading of old savegames is supported._

After our latest patch, we received a lot of reports about the long loading times that occurred when starting the game. Thank you again for your comments and patience while we were working on a solution! We have now prepared a hotfix that addresses this issue, which you can read more about below.

##### **Paradox Mods:**

- Fixed long loading times when mods are loaded at startup.

##### **Misc:**

- Info and Warning level logging no longer print callstacks to log files.

- Fixed a crash when loading a save game.

##### **Post-mortem**

When you started the game after the recent patch, you might have noticed that the startup loading times were a lot longer than in previous versions, especially if you had large amounts of mods active. Due to changes in the PDX Mods SDK, the way mods were loaded by the game added an unintentional side effect.

To be more specific, the issue causing long loading times on startup was related to mods adding new entries to localization. When new entries were added, it caused reinitialisation of the whole PDX Mods platform within the game, which is a heavy operation. This caused CPU usage to spike on loading, and it was multiplied by the amount of mods that added new localization strings. Any mod that added new localization strings was affected, whether it was a code mod or an asset mod.

We should have caught this in our testing, but our test set contained only around 100 mods. To make sure this does not happen in the future, we will increase this test set significantly and improve our mod testing in general. In the long run, we are also preparing steps to reduce the issues where new patches cause issues with mods. We will discuss this in more detail in our future City Corners.