The reduction of rate is because you save in XML format, which is an ASCII format, so human readable, but takes long to write. If you switch to binary format and write on a decent fast hard disk, you should get back to 450 Acq/s.
when I use my Evaluation Board with some PMTs I can digitize 450 Acq/s or so. But when I want to save the waveforms the rate goes down. The Acqu. rate with saving is in the range of 14Hz up to 24 Hz.
I normally use the .txt file. I try to use the 5GS/s but also with much lower sampling rate the saving rate is not getting much better.
Is this a problem of my McBook connected to the Evaluation Board?
All the best,