QtCreator becomes busy and unresponsive after editing a file

The last builds of 4.9 beta seemed to perform some calculations in the back after editing a file, so the fact is that the mouse pointer disappears within qtcreator window. It recovers after something like ten seconds. 

A possible related but separate issue is that compilation does not start immediately but after a lapse of 10 or more seconds during which Qtcreator is using a core 100%. That is a little annoying when checking for compilation errors real quick.

Applies for

Qt Creator 4.9.0-beta1 (4.8.82)

Based on Qt 5.12.1 (GCC 5.3.1 20160406 (Red Hat 5.3.1-6), 64 bit)

Built on Feb 20 2019 01:16:36

From revision c134850255

(I am not suere I am in Wayland, it is linux debian)