Slow transcoding

we currently have the problem that when we upload a video, the
transcoding of the video takes a very long until Kaltura reports back that the video is available.
We are talking about up to 45 minutes for a video of 5 MB, which is converted into 5 formats.
We host the environment ourselves!

We are using the C# interface for uploading the Files.

Our customer with whom we run the portal compares the conversion with other hosting providers like who convert the same file in less than 5 minutes.

We have already moved the servers from spinning disks to SSD, but no change. The server also has enough CPU, memory and hard disk capacity. Also from shared hardware to private hardware. but still no change.

Is there any way we can find out why it takes so long and for what?

Would it help if we disconnect the server for uploading and converting from the computer that offers streaming?

It would be great if you could give us some tips here.

Thank you very much