Bug Report: Input lag when switching between Chinese and English IME on macOS

Bug Reports
1

Description
When composing an email, switching the input method from Chinese to English using the macOS native input method editor (IME) causes noticeable lag/stuttering. This issue occurs consistently during the switch and disrupts the writing flow.

Environment

  • Device: MacBook Pro (Apple M1 Pro)

  • macOS Version: 26.4.1 (25E253)

  • Mailspring Version: 1.20.1 (1.20.1)

  • Input Method: macOS built-in Chinese/English IME

Steps to Reproduce

  1. Open Mailspring and start composing a new email.

  2. Set the input method to Chinese (macOS native IME).

  3. Switch the input method to English.

  4. Observe the lag/stutter during or immediately after the switch.

Expected Behavior
The input method switch should be seamless with no noticeable delay.

Actual Behavior
A visible lag/stutter occurs when switching from Chinese to English input, making it difficult to type smoothly.