Optimizing performance | Add shadow enabler

[Grozamir]

In my app if count nodes more 30+, so then starting freezing and downing performance. The culprit of all this's shadows. I added enabler shadow. And now in my project disabled shadows and i can spawn very more nodes

There was a problem:

[Daguerreo]

Is it everything really necessary? It should be enough to check if the "ShadowColor" key is valid/populated and only in that case instance the shadow effect.

[Grozamir]

It seems to me that it was natural to create a shadow switch.

[Daguerreo]

It seems to me that it was natural to create a shadow switch.

and what if the switch is true and the shadow color not setted?

[Grozamir]

Then the shadow color will be Black (0, 0, 0)

[nolankramer]

This is a good idea for optimizing based on user's preference between appearance/drawing performance - however it may also warrant implementing shadow drawing ourselves - since it's likely we can make assumptions that Qt isn't aware of (or use a simpler method of drawing shadows).