If you specifically need v1.4 (for example, to maintain mod compatibility for an older save), you can safely revert using Steam: Right-click in your Steam Library. Select Properties , then open the Betas tab.
: Developers reported a roughly 37% reduction in game launch and save-loading times. Download RimWorld v1.4.3550
The v1.4 update (originally released in late 2022) was a major milestone that introduced: If you specifically need v1