first you could try to add this line to your omnirc file on the media-agent
OB2IPCNOSENDRECVLOOP=1
if you only have an omnirc.tmpl file -> copy it and remove the .tmpl extension.
have you done complete update/migration of the dp installation or did you made the backup jobs new? do you have the same blocksize and concurrency configured in dp 7.03 as you had before?
you could also try create a test backup job and as backup target configure a nul device to check what backup performance you have then compared to the backup you do on your tape