I agree. Over the last couple of months I have tried to use Iceweasel, but despite it's attractive add-ons, I always end up going back to Chromium for the reasons you state. I have tried renaming the profile folder and various tweaks, but could never get it to work well. The tabs are slow to switch between, there is lots of lag on page scrolling. I also experienced crashing and hanging. I tried version 17 from jessie and 25 from sid.
One tweak that did help with the lag was changing gfx.xrender.enabled to false from about:config Daniel
