So I finally reinstalled Skyrim and a bunch of mods. I still get the warning notice for SKSE when I load up the game, saying I need to install it. But at Nexus it says the script is already included in the Steam DL. I have two problems. I get '???' for some of the tabs rather than a dedicated key. The bigger issue is there's considerable lag time when pulling up menus. Literally 3 seconds, which is an eternity given how often you have to access items. Is this normal? Any advice on how to fix this is much appreciated.

My advice? Don't use Steam to install SKSE (or any mods, really)

Here's the website for SKSE: http://skse.silverlock.org/

You can download an archive or an installer, your choice. If you want things to be most hands off, use the installer.

Yep I finally did that and the problems are solved. Seems both Steam and the Nexus installer are a bit out of date. Thanks.