Tablesorter drammatically slow on IE8

Tablesorter drammatically slow on IE8

I have a table with 900 rows and 6 columns.

Page sorted + zebra + pager, loads in 1 second with chrome, 2-4 with firefox, ..... 30 with IE8.

the same loading without presorting zebra and pager.

If i run page in "compatibility mode",  page loads fast!!

Suggestions?