Hard to tell if we are talking about the same things, but that was not my experience. After we made some adjustments we got our typical encounter down to 10-20 min., larger combats about 30 min., and boss battles about 1 hr. Our primary adjustment (which we still use in 5e) was to reduce a players turn to 30 sec max. 30 sec to determine an action, roll the attack, and roll for damage. To me the primary thing this solved was decision issues. You take those out, the game ran pretty fast.
EDIT: Just to clarify, we don't run published adventures. I created all of our 4e adventures, though I sometimes took elements from published adventures.
EDIT 2: Most of the rest of our 4e adjustments were on the DM side, so I didn't take to long! I tried to keep my turn to 20 seconds per monster, but I didn't have a hard limit really.