ID 427191 - Changing the Backdrop name gets an increasing lag depending on the amount of attributes promoted in a material

Problem summary
Changing the Backdrop name gets an increasing lag depending on the amount of attributes promoted in a material 

Customer reported version
Mari 4.6v3

Customer reported platform
windows10

Steps to reproduce

1) Create a new project and load the attached material 

2) Create the material in the NG and go inside it 
3) Select some of the nodes and create a Backdrop with them

4) Try to change the Backdrop name via the node properties 

result: Mari will become not responding 

Expected behaviour
It should take the same amount of time regardless of the attributes promoted in the material 

Actual behaviour
It gets an increasing lag depending on the amount of attributes promoted in the material 

Workaround
Unknown.

Reproduced by Manual QA

This bug has been reproduced in:

4.6v3 - Windows 10 

4.5v2 - Windows 10 

Unable to reproduce bug in:

3.3v1 - Windows 10