Have you added heaps of files to your library in the new version? If you go tools > options > My Library you'll see which folders you've added to your library. If you've added huge folders then it could take ages for LW to add those files & (?) maybe that could cause LW to freeze.
In that case try removing some folders or if you only share a single folder, try removing some files from that folder.

Otherwise, try updating your Java (or reinstall if you're already using the latest Java): Java SE Downloads
Download the JRE offline installer & remove any other Java versions before installing a new one.
Reboot your computer after installing.

If that doesn't help, try deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will change all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.
In case you're using Vista: LimeWire Pref Folder in Vista