For the OP, what the others posters have said is very true- I gave your the short version, but what they're talking about is very important to the Empire.
Unlike the Roman Empire during it's golden age, or the Byzantine Empire of say, Justinian or Heraclius, the Holy Roman Empire was not a big, united Empire.
It was very similar to the Confederate States of America, in that all the little individual dukedoms, princedoms, free cities, regions, etc., they were all for the most part loyal to the Empire in name only. No good Bavarian would trust a Thuringian. No Austrian likes a Swabian. No Saxon would feel comfortable would with a Tirollian as an overlord. It was very regional empire.
In fact, very Byzantine. Lots of infighting, petty conflicts, backstabbery, and all the nastier things of Medieval politics were very much so present in the 'German' court.