I also have pages that load some huge viewmodels, lists of like 3000-4000 things are very slow. Good to know mapping might be what is taking a large part of the time.
I wouldn't use the jquery templates. I moved away from those, the new knockout templates are faster for me not slower.
Jquery templates can also be a hassle to debug, and can sneak up on you in nasty ways, for example, if you have code like:
data-bind=" event: {change: function() { /*dosomething*/ }}" the }} characters will be interpreted as a jquery template and you will have errors.
//if you do use them, the solution is to put a space, like so data-bind="event: {change: function() { /*dosomething*/ } }" by the way