Merge pull request #4515 from Carreau/load-speedup Spring Cleaning, and Load speedup 0) prompt '*' strore fix + tab remove tooltip tab was not cancelling tooltip bringing to cases where you could have tooltip andcompleter open. Do not store '*' when serializing cells. get rid of most slowdown at notebook loading. 1) Do not setOption('mode',new_mode) on CM if new and old mode are the same. It triggert a lot of calculation of bounding box in the end. 2) Do not select cell when loading the notebook it triggers a lot of CM even that check visible things and so on and so forth. So add a option to add_cell_at_index not to select it 3) jQuery $.attr has some magics, but has a slight overhead on real native ELEM.setAttribute DOM method. Seem slight improvement when loads of PNGs on one page