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Performance and Benchmarks

Performance expectations and benchmarking for Omni CLI features.

Table of Contents

Thunderbolt 4 SSD Performance

Thunderbolt 4 provides up to 40 Gbps bandwidth. Real-world SSD performance depends on the drive quality.

Typical speeds

SSD Type Read Speed Write Speed Notes
High-end Thunderbolt 4 NVMe 2,800 MB/s 2,300 MB/s Best for swap/cache
Mid-range Thunderbolt 3 NVMe 2,000 MB/s 1,800 MB/s Very good
USB4 NVMe 1,800 MB/s 1,500 MB/s Good
USB 3.2 Gen 2 NVMe 900 MB/s 800 MB/s Acceptable for light use
SATA SSD (USB) 500 MB/s 400 MB/s Not recommended for swap

Internal vs External SSD

Modern Macs use very fast internal SSDs. A good Thunderbolt 4 external SSD can come close.

Metric Internal Mac SSD Thunderbolt 4 SSD Difference
Read ~5,000 MB/s ~2,800 MB/s ~44% slower
Write ~4,000 MB/s ~2,300 MB/s ~43% slower
Latency Very low Low Slightly higher
Endurance impact on internal SSD High Reduced Significant benefit

Benchmarking Your Setup

Test disk speed

On macOS:

diskutil info /Volumes/ThunderboltSSD | grep "Protocol"

# Simple write test
time dd if=/dev/zero of=/Volumes/ThunderboltSSD/test-file bs=1m count=1024
rm /Volumes/ThunderboltSSD/test-file

Test memory pressure impact

  1. Run a memory-heavy workload
  2. Monitor with Omni CLI:
omni memory monitor
  1. Compare performance with and without external cache

Test swap speed

# Create memory pressure and measure swap usage
stress-ng --vm 4 --vm-bytes 2G --timeout 60s

Monitor swap usage during the test.

Memory Optimization Impact

Moving app caches to Thunderbolt SSD can free significant internal storage:

Cache Type Typical Size Internal SSD Saved
Docker Desktop 10-100 GB High
Xcode DerivedData 5-50 GB High
Gradle 1-10 GB Medium
npm 1-5 GB Medium
Python pip 0.5-2 GB Low-Medium

Expected Improvements

For developers

  • More free space on internal SSD
  • Reduced wear on internal SSD
  • Better sustained performance under memory pressure
  • Faster Docker builds when cache is on fast external SSD

For content creators

  • More room for project files on internal SSD
  • Reduced risk of running out of disk space

Caveats

  • Initial cache migration takes time
  • External SSD must remain connected during use
  • First access to moved caches may be slightly slower than internal SSD
  • Not a replacement for insufficient RAM in all cases