Performance

psmux is built for speed. The Rust release binary is compiled with opt-level 3, full LTO, and single codegen unit. Every cycle counts.

Metric	psmux	Notes
Session creation	< 100ms	Time for new-session -d to return
New window	< 80ms	Overhead on top of shell startup
New pane (split)	< 80ms	Same as window, cached shell resolution
Startup to prompt	~shell launch time	psmux adds near-zero overhead; bottleneck is your shell
15+ windows	✅ Stable	Stress-tested with 15+ rapid windows, 18+ panes, 5 concurrent sessions
Rapid fire creates	✅ No hangs	Burst-create windows/panes without delays or orphaned processes

How It's Fast

• Lazy pane resize: only the active window's panes are resized. Background windows resize on-demand when switched to, avoiding O(n) ConPTY syscalls
• Cached shell resolution: which PATH lookups are cached with OnceLock, not repeated per spawn
• 10ms polling: client-server discovery uses tight 10ms polling for sub-100ms session attach
• Early port-file write: server writes its discovery file before spawning the first shell, so the client connects instantly
• 8KB reader buffers: small buffer size minimizes mutex contention across pane reader threads

Note: The primary startup bottleneck is your shell (PowerShell 7 takes ~400-1000ms to display a prompt). psmux itself adds < 100ms of overhead. For faster shells like cmd.exe or nushell, total startup is near-instant.