In late 2020, Microsoft’s compatibility team added Assassin’s Creed Black Flag to the "FPS Boost" list. If you own an Xbox Series S or X:
The Result: The game runs at a near-locked 60 FPS. The Catch: To achieve this, the Xbox runs the Xbox One S version of the game at 1080p (Series S) or 1440p (Series X). You lose the 4K resolution upgrade. Furthermore, it is still locked at 60 — not higher.
For Series X owners, this is a decent compromise. But for PS5 and PC users wanting 120 FPS, we need the heavy artillery.
Before we dive into the "how," we must understand the "why." Unlike modern games that separate rendering from logic, older iterations of the Anvil engine (used in AC3 and AC4) used a double-buffer vertical sync (V-Sync) system tied to the simulation clock. assassin 39-s creed black flag 60 fps unlock
When you run Black Flag at 60 FPS, the simulation step runs every 16.6 milliseconds. If you force the game to run at 120 FPS, the simulation step doubles. Consequently:
Ubisoft never officially patched this because a remaster was not financially viable. The community was left to pick up the pieces.
The method depends entirely on where you play. Let’s break it down. The Result: The game runs at a near-locked 60 FPS
Set your desktop refresh rate to 120Hz. Launch Black Flag in Borderless Window mode. The Windows Desktop Window Manager (DWM) sometimes forces a higher refresh rate without triggering the physics engine. This yields ~80-100 FPS with minor swimming glitches.
On paper, going from 30 to 60 FPS sounds like a technical number. In practice, it changes the entire feel of the game. The original 30 FPS cap gave the game a slightly "heavy" or sluggish feel, typical of last-gen ports.
Unlocking the framerate strips that weight away. Edward Kenway moves with a fluidity that makes navigation a joy rather than a chore. Parkour feels snappier, and the lag between pressing a button and seeing an animation trigger is drastically reduced. When you are leaping from mast to mast in the middle of a storm, the extra frames provide clarity that makes the platforming significantly less frustrating. Before we dive into the "how," we must understand the "why
For years, the solution to the 60 FPS lock was "don't do it." Then, modders cracked the code. The current gold standard is "Black Flag 60 FPS Unlock + Fix" by various community members (most notably XXX and Rose on the Black Flag Modding Discord).
Here is the technical breakdown of what the modern mod does: