Tdesktop: 100% CPU usage and slow input response when Windows spellchecking is enabled

[grandsilence]

Steps to reproduce

1. Open settings and enable system spellchecking
2. Open any chat tab
3. Write a lot of symbols in chat textbox like:

......................................................................................................................................................................................................................................

Expected behaviour

Spellchecking method should be called only once, 200 ms after the last input, not on every key press (debounce event via timer required).

Actual behaviour

On each symbol type Telegram calling spellcheck method and load CPU on each key press.

Configuration

Operating system: Windows 10 1803
Version of Telegram Desktop: 2.4.3
Used theme: Default

[ilya-fedin]

Are you sure that this is due to the spellchecker? Telegram writes drafts synchronously to disk on each text write and that may cause the same behavior, there are an issue for that already:#7952 (the issue is cross-platform even though reported by a Linux user)

[grandsilence]

@ilya-fedin Yes, I'm sure. If I turn off grammar checking, CPU consumption is 0.1% for Telegram.exe. I just checked it out.

[grandsilence]

Looks like #8612 already reported about it.

[ilya-fedin]

200 ms after the last input

Just wondering, why 200ms exactly?

[grandsilence]

@ilya-fedin 100-200ms is average value of user reaction. So it's a good value for debounce / throttling events.

[ilya-fedin]

Thanks.

[23rd]

Thanks for your report, I'll check it later.

[23rd]

@grandsilence Are you sure that pure dots without any letter are the cause of high CPU usage?

[grandsilence]

@23rd Yes, I’m sure. Just dots cause of 100% cpu usage. I can make a GIF.

[23rd]

I can make a GIF.

I would appreciate it.

[grandsilence]

@23rd GIFs:

Spellchecking is ON

Spellchecking is OFF