This might help a bit (not tested):
jQuery("tr.Grid_Item,tr.Grid_AltItem").each( function() { // Use tr to
skip checking nont-tr-elements
var td_nodes = jQuery(this).find('td'); // Get the td nodes
with a single select and store them in a variable
var Id = td_nodes.eq(2).text();
var foo = td_nodes.eq(8).firstchild.attr("value");
var bar = td_nodes.eq(9).firstchild.attr("value");
});
There are other ways to optimize things but for further advice more
info would be needed on what you are actually trying to accomplish.
Looping over thousands of rows and dynamically fetching data is bound
to be a bit slow, as DOM-access always has it's overhead. There are
other more efficient ways to accomplish the same things, usually (such
as storing all the necessary data in a javascript-object which gets
updated when the values change. You can get _much_ faster response
from getting / calculating the values from there when you need them,
instead of looping all over the DOM every time).
