Revit Material "Appearance" is slow

[MachielAEC]

The Revit Material Appearance Tab is really slow when I open it up.

The material browser opens up it's normal (slow) speed without any issues. The moment I select the Appearance Tab it takes a bit of time to open up and when it does, It won't load my materials - yellow exclamation mark.

This is on Revit 2020 and I've checked the following:

1. Material set to Draft render (not production)
2. Graphics card drivers up to date (NVidia GeForce GT 540 M)
3. Revit 2020 with all updates installed
4. Latest Windows updates ran.

Any advice?

[joe_keogh]

I had the same issue recently, which was due to my C: drive having less than 20Gb of free space.  

The exclamation marks are indicating that the material has a legacy Appearance asset assigned to it.  this is not a big deal, you can replace the Appearance asset, or use the old one, check here

[MachielAEC]

Thanks for the info regarding the HDD space. Will test that out to see if it will improve performance.

Regarding the !-mark, I'm aware of the marking in the "search bar" however the !-mark i'm getting is when you look at the preview window for the assets (appearance window) - normally the sphere or cube when you are creating a new material.

[joe_keogh]

I see,, and if you hover over the exclamation mark, does it reveal the warning?

[MachielAEC]

Only what you are seeing in Image 2.

"Failed to load preview, refresh window...."

[joe_keogh]

In that case I am guessing this is an issue with the GPU 

[MachielAEC]

I've checked the HDD, it's a 250 GB SSD with about 18GB free at this stage.

My initial thought was also that it's the GPU, I think it just to old (release date back in 2011).

Was just initially weird as everything is working perfect, speed is not an issue until you open the Appearance Tab under the Material Library then it slows down completely.