I know this is an old thread, but I thought I'd bring it back since I solved the problem in my case.
I just purchased a 2002 X5 3.0 (with Nav, no DSP) this week which had the problem of a several second delay when tuning to stations via the presets with RDS enabled. What was strange was that I could not bring up the option to disable the RDS on the radio. Looking through my car's repair history, I saw that the radio tuner had been replaced under warranty. Then, further searching indicated a bulletin from BMW regarding this issue. The bulletin stated that the radio is coded improperly and should be replaced.
Well, instead of replacing the radio, I recoded it (yes, I have the tools to do so
). That completely fixed the problem. Tuning to preset stations no longer has any delay.
Hope this helps,