make UI more responsive

[jtorjo]

1. When opening a log, and we're showing/hiding columns -> this is seen visually (as if, most columns are hidden, and then some are re-shown). I should be able to make this in one step. Note: seen as the application starts, when some columns are hidden
2. When the log is big, and it's the first thing we open, and we also need to move to a saved position+size, and some toggles are on/off (especially Alt-T), it takes a bit for the UI to redraw, and just doesn't look cool

note about 1. - this happens when the column positions are not cached. Thus, we have added lots of rows before really showing/hiding columns. Not sure what I can do about it