Severe slowdown when using offline and heavy files in Delphi

thank you
I use MapWinGis ActiveX in Delphi10.3 and in offline Mode.
I faced two big problems.
First, it is not possible to load ECW files
Secondly, when I use Tiff files with a size of about 5 GB, the speed of loading, zooming and moving is drastically reduced, so that the Redraw time takes up to 50 or 60 seconds!
How can this problem be solved?
Thank you for your kindness and guidance

ECW support will be back with the next version when we use GDAL3+.
The bleeding edge version can be downloaded at Actions · MapWindow/MapWinGIS · GitHub
Not sure how it works in Delphi though :wink:

You can add overviews to the tiff. That should speed up the drawing.
The documentation site is currently down (we’re working on it) but the Image class has an Image.BuildOverviews().

Thank’s pmeems
When will the new version be ready?
And how can i use of Image.BuildOverviews()
When and in which Event?

We don’t have a date for the next version.
A lot of work still needs to be done regarding the migration from PROJ.4 to PROJ.7+
We aim around the end of March 2022.

Before you open the image or load it as a layer you can call GdalUtils.GdalBuildOverviews() to create the overviews.

According to your order, I used GdalUtils.GdalBuildOverviews() command as follows

First I defined a variable
MyGdal : GdalUtils;

MyGdal := CoGdalUtils.create;

Then Load Image…

But I encountered some problems, it is very slow (in zooming, moving the layer, etc.) and the layers are black when drawing.

In order to debug this properly, I need the image you have trouble with.
Can you share it? If not publically you can share it directly with me using something like and my e-mail address bontepaarden[at]gmail[d0t]com.