How to Track Down CPU Spikes With the Profiler

Optimizing by guesswork wastes days. A profiler trace shows exactly where the frame went. Here is how to read it.

How to fix it

1. Capture during the spike

Record a deep profiler capture while reproducing the spike so the trace contains the actual hot frame.

2. Find the hot stack

Sort by self time on the main thread to find the real hotspot instead of optimizing cheap code that merely looks suspicious.

3. Verify the win

Re-profile after each change so you keep optimizations that actually move the frame time and revert ones that do not.

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.