A lightweight macOS menu bar utility for real-time system monitoring.
CPU · Memory · Disk · Battery · Thermal · Top Processes

macOS Activity Monitor is powerful but heavy. Third-party monitors are bloated with features you don't need. Performance Viewer gives you the essentials — always visible in your menu bar, one click away from details, zero background overhead.

Performance Viewer runs as a menu bar agent (no Dock icon, no main window). A background timer refreshes all metrics every 2 seconds using low-level macOS APIs:

Performance/
├── PerformanceApp.swift                 # @main — MenuBarExtra scene + login item
├── Models/
│   └── SystemStats.swift                # Sendable value types with computed formatting
├── Services/
│   └── SystemMonitor.swift              # @Observable — Mach, proc_*, IOKit collection
└── Views/
    ├── MenuBarPopover.swift              # Main UI — stats grid, details, processes, footer
    └── Components/
        ├── ProcessRowView.swift          # Process row with rank, name, memory
        └── GaugeRingView.swift           # Reusable circular gauge component

Design principles:

• Pure SwiftUI with @Observable (Swift Observation framework)
• Zero third-party dependencies — only Apple frameworks
• Sendable models for thread safety
• Color thresholds adapt to load (green → orange → red)

• macOS 15.0 (Sequoia) or later
• Xcode 16+ to build
• App Sandbox disabled (required for proc_pidinfo, IOKit, and Mach APIs)

git clone https://github.com/sanztheo/PerformanceViewer.git
cd PerformanceViewer/Performance
open Performance.xcodeproj

Press ⌘R in Xcode. The app appears in your menu bar.

Contributions are welcome! Some ideas:

• Per-process CPU usage tracking
• Network throughput monitoring
• GPU utilization (Metal Performance HUD)
• Configurable refresh interval
• Sparkline history graphs in the popover
• Notification alerts for high usage thresholds

MIT

_{Built with SwiftUI · No dependencies · Open source}