Description:
With the GTK+3 VCL, keyboard text entry in Word and Calc (other modules untried) is extremely sluggish.

OpenGL is not enabled.

Same problems occurs with new user profile.

The extremely sluggish text entry behavior does not occur in dialogs such as "File Open" or "Save As" etc.  It only occurs with text entry in a Word document or Calc cell.  Also, cell movement using the arrow keys is uneffected.

This would indicate that the sluggish text entry is possibly related to font rendering.

I am using libreoffice-6.3.4.2 with GTK+2 as this is the last version that uses GTK+2.  All higher versions use GTK+3 and exhibit the extremely sluggish keyboard text entry.

Steps to Reproduce:
1. start LO with SAL_USE_VCLPLUGIN=gtk3 (or allow auto-determination at at startup)
2. invoke Word or Calc
3. enter text with keyboard

Actual Results:
Allow LO to determine at start up the VCL plugin to use, or set SAL_USE_VCLPLUGIN=gtk3 in programs.soffice.


Expected Results:
Text entry with keyboard should be the same speed as all other applications and as is set with X Window configuration.


Reproducible: Always


User Profile Reset: Yes



Additional Info:
Version: 6.3.4.2.0+
Build ID: Gentoo official package
CPU threads: 8; OS: Linux 5.6; UI render: default; VCL: gtk3; 
Locale: en-US (en_US.UTF-8); UI-Language: en-US
Calc: threaded

Although this is the Gentoo version, the same problem occurs with LO binary distribtion from libreoffice.org.