How to Fix Movement Speed Drift From a Client-Server Tick Rate Mismatch

Authoritative movement must advance by the same delta on client and server. When the client multiplies velocity by a variable frame delta but the server uses a fixed tick, predicted and authoritative positions accumulate a speed difference.

How to fix it

1. Adopt a fixed timestep accumulator

Accumulate real time and run a fixed number of simulation steps (e.g. 60 Hz) on both client and server, carrying the leftover remainder to the next frame for rendering interpolation.

2. Apply movement per simulation tick

Multiply velocity by the fixed tick duration, never the render frame delta, so the same input over the same number of ticks always covers the same distance everywhere.

3. Match the constant on both builds

Define the tick rate in shared code so client and server cannot drift apart when one side's constant is changed without the other.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.