jquery-ui-bootstrap/jquery-ui-bootstrap — pull request #232 by Koloto (2014-02-18 15:17:55+00:00)
Title: Removed '.ui-widget :active' selector because of the performance problem

I found a very slow selector:

.ui-widget :active {
outline: none;
}

I have a complex HTML page containing a large grid (with more than 500 rows). After importing `jq-ui-bootstrap.less` every click lasts about 500ms. Delay is the same even if there isn't any ascendant element with `.ui-widget` class.
After some experiments I found that the reason of these lags is the selector above. When I comment it, all works fine. I don't know why this selector is so slow, but it's bad practice to use the descendant selector in any case. I suppose `outline: none` was introduced mostly for `` tags. But it was already done in Bootstrap, see 'normalize.less':

a:active,
a:hover {
outline: 0;
}

So I think the selector `.ui-widget :active` can be safely deleted.