So, we have this product, and it is very slow in IE. We have already applied many methods recommended by the guys from IE ( this one and this one ) and are trying to sacrifice clean code for performance in critical parts, such as manipulating the DOM.
However, as you can see in this screenshot, IE profiler. 
Just "String" is the biggest criminal. Nearly 750 ms of exclusive time.
Does this mean that IE spends 750 ms creating instances of Strings? I also read this stuff on the Opera Dev blog :
The build script can remove spaces, comments, replace strings with searches in the array (so that MSIE does not create a string object for each individual string instance - even under conditions)
But there is no more information about this. Can anyone clarify? It seems like IE should create a full instance of String every time there is a "" in your code, which might explain this, but I don't know what the search optimization in the array will look like. BTW- we don’t actually do most of the string concatenation anywhere in the code.
The library we use is MooTools 1.2.4.
Any suggestions would be appreciated! thank
UPDATE- " ". (1 ), , JS. , , .
, - , String.prototype ?