Very slow to see media thumbnails in charged folders or in media navegator

Hi, I have a very annoying issue for a very long time to see and navigate the video media charged to the project or looking for media.

When I open a folder and I change the view to thumbnails all the files appear like a file graph and it takes a very long time to appear the thumbnail of the video. What it makes the work very slow because every time I open a folder I have to wait the thumbnails.

The same happen when I use the media navigator to charge new videos to the project.

I thought that was because I have a mackbook pro 13 2012 with external normal HDD.

But now I have a i7 quad 2017 plus external SSD 2tb very fast and its the same, a very little better but anyway slow and annoying.

Is there any way to get a very fast view of the thumbnails videos?

I will love advise on that

thanks

nico