Abnormal memory or CPU usage: where it comes from
Normally Clash for Windows sits at one-to-two hundred MB of RAM (Electron UI + core) and near-zero CPU. When it stays high, check the sources in order:
- Connection storms: P2P downloads (BT, some cloud drives) open thousands of simultaneous connections that the core tracks one by one — CPU and RAM climb together. Confirm via the total on the Connections page; a direct rule for the download tool (or keeping it off the proxy) helps immediately;
- debug logging left on: debug emits floods every second. Switch log-level back to info/warning after a debugging session;
- The window stays open: live charts and the connection table cost rendering. Close the main window (minimize to tray) and the UI's share of usage disappears — the core keeps working;
- Huge rule sets updated too often: hundreds of thousands of entries with a short interval means frequent fetch-and-parse cycles. Trim/merge sets and relax the interval to a day.
Quick triage
- In Task Manager, is the UI process or the clash core process hot?
- UI hot → close the window, keep the tray. Core hot → check connection counts and log level;
- Still bad → restart the app, and check whether an AV keeps rescanning it (whitelist).