Performance Budgets

The runtime targets 60 FPS with a stable frame time and predictable memory use. Budgets are estimates; update them as measurements are collected.

Targets

Frame time: 16.6 ms (60 FPS)
Main thread CPU budget: 6 to 8 ms
JS budget: 2 to 4 ms (depends on scene complexity)
Shim + command translation: 1 to 2 ms
Present and GPU submission: 1 ms (CPU side)

The GPU budget is scene-dependent and not included in the CPU budgets above.

Napkin Math Template

RESOURCE BUDGET: [Feature Name]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Memory:
  Per-item size: ___ bytes (struct + padding)
  Max items: ___
  Total: ___ MB/GB
  Cache analysis:
    L1 (64KB): fits ___ items
    L2 (512KB): fits ___ items
    L3 (16MB): fits ___ items
  Verdict: PASS/FAIL

CPU:
  Operation: ___
  Cycles estimate: ___
  At 3GHz: ___ ns
  Per-second throughput: ___
  Verdict: PASS/FAIL

Latency Budget:
  Target: ___ ns/us/ms
  Breakdown:
    - Step 1: ___ ns
    - Step 2: ___ ns
    - Total: ___ ns
  Safety margin: ___x
  Verdict: PASS/FAIL

Conclusion: PROCEED / REDESIGN

Example Budget: Event Queue Drain

Assumptions:

512 events max per frame
120 cycles per event to normalize and dispatch

Estimate:

512 * 120 cycles = 61,440 cycles
At 3GHz: ~20.5 us

Verdict: PASS (well under 1 ms)

WebGL Call Budget

Early milestones assume:

2,000 to 5,000 WebGL calls per frame
200 to 500 draw calls per frame

The shim state cache must avoid redundant state changes to stay within budget.

Startup Budget

Targets for cold start:

App window visible: < 1.0 s
First frame rendered: < 2.0 s

These numbers are placeholders and should be validated against real demos.