CPU usage is high a little

### Observed

When I open the SimpleNote web page or the Electron App, the CPU usage increases by about 5%.

When I analyzed the Performance in Google Chrome's Developer Tools, I found that the timer was firing about 250 times per second. This phenomenon may be related to the high CPU usage.


### Expected

CPU usage does not increase significantly by just opening the SimpleNote application.

### Reproduced

1. Open Electron app
2. watch the CPU usage by top command

This problem occurs on both of Electron app and web browser.

### Where did you see the bug
- System Make:
- System Model:
- OS:Ubuntu Linux
- OS version: 20.10
- Browser (if applicable): both of Electron App and Google Chrome
- Browser version (if applicable): Version 89.0.4389.114
- Simplenote app version: 2.9.0-beta

No source file, test, or entry point is named. Reproduce the issue in the Electron app and Chrome, then use Chrome Developer Tools and top to investigate the timer firing about 250 times per second. Done means opening Simplenote no longer causes a significant CPU increase in either environment.

Written by the indexing model from the issue text.