Game performance: measure, find the cause, prove the fix

Never fix performance from a guess. Agents (and people) who skip the measurement change the wrong thing, then report a win nobody measured. Get numbers, change one thing, get the same numbers again.

1. Know the budget

Average fps hides stutter. A game can average 58 fps and still hitch every few seconds. Report:

• p50 (the typical frame), p95 and p99 (the bad frames), and the worst frame, all in milliseconds;
• hitches: frames over about twice the budget, counted per minute;
• the counts that explain them: draw calls, triangles, live objects or nodes, memory.