I think this idea of the removing icons in the grid is not well thought out idea. Those icons told the user where they were. For my company, we have many custom entities that look very similar. The icon was useful to show the user what they were looking at rather quickly. Now they are forced to look at the top of the grid to a plain text label that says "Accounts" or try and find out where their currently selected area is in the left menu. Plus, the iconds just plain-old looked good. It think this is a major step backwards.
Also, I don't think the loading of 250 icons would speed things up. The icon has to be loaded only once by the browser and then is used many times.