Keytable processing slow after adding FixedColumns to table

I have a table with about 50 rows and 20 columns that utilises the KeyTables addin to support cursor key cell navigation. ie, up, down, left, right.

I recently I added the FixedColumns addin to fix the header and first column in place. Works well, however, the cursor key navigation and for that matter, any "cell setfocus" operation now takes a noticeable time to execute - typically more than a second. If I turn off the FixedColumns the speed goes back to normal.

Profiling reveals that most of the time (~680ms) is spent in _fnSetFocus of KeyTable.js which seems to be doing a lot of element cloning.

Any ideas what I can do to speed this up?

I'm using: jQuery 1.7.2, DataTables 1.9.1, FixedColumns 2.0.3 and KeyTable 1.1.6.

Thanks.
Glenn.