feat: add comprehensive getSlots performance tests for complex team scenarios

[devin-ai-integration]

Performance Tests for getSlots Logic with Complex Team Scenarios

Summary

This PR adds comprehensive performance tests for the getSlots logic to measure and analyze slot generation performance with complex team configurations. The tests were specifically created to evaluate a recent performance optimization and provide ongoing performance monitoring capabilities.

Key Features:

• Complex Team Setup: 8 round-robin hosts + 1 fixed host across diverse timezones (India UTC+5:30, Venezuela UTC-4, Netherlands UTC+1)
• Realistic Schedules: Working hours with lunch breaks, date overrides, and timezone-specific availability patterns
• Multiple Scenarios: Tests for ROUND_ROBIN vs COLLECTIVE scheduling, host count scaling (2-8 hosts), and date range impact
• Performance Analysis: Before/after comparison showing 0.5-3.7% performance improvements from recent optimization
• High Slot Volume: Generates 300-1200+ slots per test (vs previous ~96) for more meaningful analysis

Performance Results:

• Baseline (2 hosts): 3.7% improvement (94.49ms → 90.96ms for 1271 slots)
• Complex scenarios (8 hosts): 0.5% improvement (114.06ms → 113.46ms for 408 slots)
• ROUND_ROBIN scheduling is ~2x faster than COLLECTIVE scheduling

Review & Testing Checklist for Human

• Verify test data realism: Review the timezone configurations, schedule patterns, and team setup to ensure they reflect realistic Cal.com usage scenarios
• Validate performance measurement methodology: Confirm that process.hrtime() timing and slot counting provides reliable, comparable metrics
• Test for flakiness: Run the performance tests multiple times to check for timing variability and environmental sensitivity
• Review before/after comparison validity: Ensure the performance comparison between commits is meaningful and the claimed improvements are statistically significant
• Check hardcoded dependencies: Verify that user IDs, dates, and timezone configurations work across different environments and don't break over time

Recommended Test Plan:

1. Run TZ=UTC yarn test packages/lib/getSlots-performance.test.ts multiple times to check consistency
2. Verify tests pass in CI environment with different timezone settings
3. Review performance metrics against actual production slot generation patterns
4. Test with different date ranges and team configurations to ensure robustness

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    PerfTest["packages/lib/<br/>getSlots-performance.test.ts"]:::major-edit
    Analysis["/home/ubuntu/<br/>performance_analysis_summary.md"]:::major-edit
    BookingScenario["apps/web/test/utils/<br/>bookingScenario/<br/>bookingScenario.ts"]:::context
    SlotsCore["packages/lib/<br/>slots.ts"]:::context
    AvailableSlots["packages/trpc/server/<br/>routers/viewer/slots/<br/>util.ts"]:::context
    
    PerfTest --> BookingScenario
    PerfTest --> AvailableSlots
    AvailableSlots --> SlotsCore
    PerfTest --> Analysis
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit  
        L3[Context/No Edit]:::context
    end

classDef major-edit fill:#90EE90
classDef minor-edit fill:#87CEEB
classDef context fill:#FFFFFF

Loading

Notes

• Session Details: Requested by [email protected] (@emrysal) - Devin Session
• Performance Optimization Context: This test suite was created to measure the impact of a recent perf: Faster logic by preventing instanceof Dayjs in slots.ts optimization
• Test Infrastructure: Leverages existing Cal.com test patterns from bookingScenario.ts and follows established performance testing conventions
• Future Value: Provides ongoing performance monitoring capabilities for the critical slot generation logic
• Risk Assessment: Medium risk due to test complexity and environmental dependencies, but provides valuable performance insights for a core Cal.com feature

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2 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
cal	⬜️ Ignored (Inspect)			Jul 17, 2025 10:22pm
cal-eu	⬜️ Ignored (Inspect)			Jul 17, 2025 10:22pm

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[delve-auditor]

✅ No security or compliance issues detected. Reviewed everything up to 51b5019.

Security Overview

• 🔎 Scanned files: 2 changed file(s)

Detected Code Changes

Change Type	Relevant files
Enhancement	► getSlots-performance.test.ts     Add comprehensive performance test suite ► performance_analysis_summary.md     Add detailed performance analysis results

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