Knockout.js incredibly slow under semi-large datasets
Please see: Knockout.js Performance Gotcha #2 - Manipulating observableArrays
A better pattern is to get a reference to our underlying array, push to it, then call .valueHasMutated(). Now, our subscribers will only receive one notification indicating that the array has changed.
As suggested in the comments.
Knockout has it's own native template engine associated with the (foreach, with) bindings. It also supports other template engines, namely jquery.tmpl. Read here for more details. I haven't done any benchmarking with different engines so don't know if it will help. Reading your previous comment, in IE7 you may struggle to get the performance that you are after.
As an aside, KO supports any js templating engine, if someone has written the adapter for it that is. You may want to try others out there as jquery tmpl is due to be replaced by JsRender.
Use pagination with KO in addition to using $.map.
I had the same problem with a large datasets of 1400 records until I used paging with knockout. Using $.map to load the records did make a huge difference but the DOM render time was still hideous. Then I tried using pagination and that made my dataset lighting fast as-well-as more user friendly. A page size of 50 made the dataset much less overwhelming and reduced the number of DOM elements dramatically.
Its very easy to do with KO: