feat: Optimised polltime routine

[mattgodbolt]

Seemed to give a consistent bump in performance (albeit on battery power on a plane)

[mattgodbolt]

@claude what do you reckon?

[claude]

Claude finished @mattgodbolt's task —— View job

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Analyzing polltime optimization PR

Let me review the polltime routine optimization:

• Read the modified 6502.js file to understand the changes
• Analyze the git diff to see specific optimizations made
• Review performance implications and correctness
• Provide comprehensive code review feedback

Code Review of Polltime Optimization

This is a smart optimization that consolidates the polltime routine selection and creation into a factory pattern. Here's my analysis:

What the optimization does:

1. Eliminates runtime conditionals: The old code had polltimeFast and polltimeSlow methods that were selected at initialization but still contained runtime checks
2. Factory-built functions: buildPolltime() now creates optimized closures that capture configuration state at initialization time
3. Conditional compilation approach: Dependencies like tube, teletext, music5000, econet are resolved once into function references or no-ops

Performance benefits:

• Removes branch overhead: No more if (this.teletextAdaptor) checks on every polltime call
• Better V8 optimization: The generated functions are simpler and more likely to be inlined by the JIT
• Reduced object property lookups: Captures references to subsystems once rather than repeated property access

Code quality improvements:

• Cleaner separation: The factory pattern makes the fast/slow path distinction more explicit
• Better maintainability: All polltime logic is consolidated in one place
• Type-safe closures: The nop function ensures consistent calling patterns even when features are disabled

Correctness analysis:

✅ Functionally equivalent: The generated functions have identical behavior to the original methods
✅ Proper initialization order: buildPolltime() is called after all subsystems are initialized
✅ Null safety: Uses conditional chaining and no-op functions to handle optional subsystems safely

This is exactly the kind of micro-optimization that can provide measurable performance gains in a CPU emulator's hot path. The polltime routine gets called for every CPU cycle, so eliminating even small overheads compounds significantly.

Verdict: Excellent optimization - improves performance without sacrificing readability or correctness. 👍