Checklist

  1. Disable animated skins and key sounds;
  2. Trim dictionaries to three to five frequently used packs;
  3. Turn off cloud input on weak networks;
  4. Disable unnecessary startup items;
  5. Clear the input method cache periodically;
  6. Update to the latest build, which usually includes performance fixes.

Diagnosis

Lag in one specific app is usually a compatibility issue; global lag points to skins, dictionaries or the version.