I was experiencing extremely high CPU usage (900%+) after only a bit of use when running WebOne in a Docker container on an Apple Silicon Mac. The proxy would become unusable and the container would consume all available CPU cores.

After investigating, identified three independent issues that compound under load:

1. Log writer spin-wait

LogAgent.WriteLine spawns a Task for each log message that busy-waits with while (!LogStreamWriterReady) { }. Under high connection volume, these Tasks pile up and spin, burning CPU cycles.

2. Regex patterns recompiled on every request

The default configuration has ~140 Edit rules with regex patterns. Each request recompiles these patterns via new Regex() calls in hot paths like HttpTransit.ProcessTransit(). Regex compilation is expensive.

3. Byte-by-byte tunnel I/O

The tunnel servers (HttpSecurePassthroughServer, HttpSecureNonHttpServer, HttpSecureNonHttpDecryptServer) read and write one byte at a time using BinaryReader.ReadByte(). This causes excessive system call overhead for every byte transferred.

Solution

1. Log writer: Replace spin-wait with lock() synchronization
2. Regex: Cache compiled Regex instances in a ConcurrentDictionary with 5-second timeout
3. Tunnel I/O: Use 8KB buffered reads/writes instead of byte-by-byte

Testing

• Before fixes: 900%+ CPU, container unusable
• After fixes: 0.03% idle, peaks ~7% under load with multiple browsers + Dropbox through the proxy
• Tested on macOS with Apple M4. Originally ran via Rosetta (x86 emulation), then recompiled for native ARM64 — high CPU issue occurred on both.

Note

This fix was developed with assistance from Claude Opus 4.5. All changes were tested on my local environment before submission.