I have had massive problems with the HRE in 3.14. How bad? My best game is now in 1135 and I have 8 provinces with Switzerland the southernmost and this is the best out of about 10 games.
The usual gangbang started but I got lucky and after a few losses in the ensuing civil war, Bohemia, Bavaria, Austria, Tyrolia and Burgundy were lost but it cut of contact with the Italians and Hungarians. The forces I withdrew from those provinces let me garrison the few I had left effectively and a few years later the French and Poles asked for ceasefires. A few years after that Lorraine and Champagne revolted from the French under an onslaught by the English and I got to grab them giving me my current 8 provinces. The only time I was happy to see a civil war

Dojorat I feel exactly the same way about the lack of cavalry, Spears, Archers and Heerban just aren't enough to stop anyone and cav is thin on the ground. After the civil war I had time to tech up some provinces for Mtd X-bows and Dienstlute and now have Swabian Swordsmen but I am a long way behind everyone else in numbers and quality. I have no idea if I am going to survive this game.

One strat that works when I can pull it off is to raze Ile de France if I capture it. That really slows the French down and as the province is nothing but farmland to the HRE the buildings are no great loss but a great income. I do the same for any non-homeland province.