Barcode Scan very slow on Terminal

Hi experts,

I have a simple dynpro, only a char field where i scan a barcode (in my case it's a GS1).

Example #9151612299#10155613203#90B2^1

When I scan this on my terminal with local GUI, it takes seconds until the barcode is "entered" completly.

When I scan this on my terminal into notepad, it's there almost directly.

When I scan this on my terminal with Citrix, it's there almost directly.

When I scan with the same scanner on a "normal" PC, it's there almost directly.

I tried with different GUI versions, (730, 740), different patch levels, did all windows updates etc. --> nothing, it takes seconds on local GUI.

What can be the problem? (already checked SAPGUI settings)

Thanks

Michael