Cursor rule

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6# Performance Rules for Fasten
7 
8## Targets
9- Small: <100ms, <10MB; Medium: <500ms, <50MB; Large: <2s, <200MB; XL: <10s, <500MB.
10- Lexer: >1MB/s; Parser: >500KB/s; Optimizer: >2MB/s; Codegen: >5MB/s.
11- Cold start <50ms; base memory <5MB.
12 
13## Benchmarking
14- Use provided benchmark framework; warmup, multiple iterations, throughput checks.
15- Assert performance targets in tests; fail on regression >10%.
16 
17## Memory
18- Use ArenaAllocator for temp data; Pool for frequent allocations.
19- Profile memory; zero tolerance for leaks; peak usage <2x input size.
20 
21## Optimization
22- Minimize allocations in hot paths; use stack allocation when possible.
23- Profile before optimizing; document all optimizations.
24- Use efficient data structures (interning, compact AST).
25 
26## Monitoring
27- Collect and log metrics (time, memory, compression ratio).
28- Alert on slow bundling, high memory, poor compression.
29- Run performance and memory tests in CI.
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