The change the old thread was about only affected network drives. Looking up a localized name for a local file should not be slow, unless something is wrong with a component in the system (typically shell extensions something else has installed, which can participate in name lookup),
Working out which item(s) in the library are causing the slowdown would help know what's going wrong.
Check that the library isn't pointing to any network drives (it could be without you realising), and that it doesn't contain any softlinks or similar pointing to them.
If the library contains more than one folder, try including just one folder at a time to see if the problem is due to something in a particular folder, allowing us to focus there.
Process Monitor logs of what happens during the delay may reveal the issue as well.