Debugging with DS-5 and USB-Blaster II slows down target cpu

Hello,

i've actual a problem while debugging my baremetal application on target.

I'm using the DS-5 and the USB-Blaster II on a custom board.

Debugging works fine, but now I've a situation where the Debugger seems to slow down my target.

at UART0 I've a connection between two controllers, running at 1Mbaud and I'm going to transfer a large amount of data.

For the data tansfer from and to the UART a DMA transfer is used and as long as no Debugger is connected everything works fine.

With no debugger connected this transfer will take approx. 20seconds.

If I've an debugger connected, the transfer will take about 2 minutes!

So anyone here, who have an Idea?

regards!