Extreme lag when opening folders, new tabs, dragging/minimizing any windows. and clicking on any text box When I use Finder, whenever I open or close a folder, even if it just has a single text file inside, my computer completely freezes for 30 seconds to one minute.  In addition, whenever I click the green button to unfullscreen a fullscreen application, my computer lags for 5-10 minutes, and does so again if I try to drag the application.  The computer also lags for a minute  when closing any application.  

A possibly related issue is less extreme lag when clicking on any text field, regardless of if its in a chrome browser or part of the OS.  Even clicking on the title and body sections when asking this question induced 15 second freezes each.  This text lag affects the login screen.

My computer can still run KSP and Minecraft easily, so I don't think its a CPU problem (though my computer lags if I click on a text field in those games).

Additionally, the first tab, be it in Safari or Chrome, that I open after each midnight takes 5-10 minutes to open.

Restarting and resetting NVRAM has no effect.
spindump is used by various system components to create reports when an unresponsive application is force quit. Reports are stored at:
/Library/Logs/DiagnosticReports/


So what you could do is to have a look at that directory to see which application required a lot of forced quits (aka crashes). Please raise a new question if you need help in reading the log.

In the meanwhile you can do the following to keep your system usable:

Keep a Terminal window open
When the system slows done to a crawl, switch to Terminal (via CmdTab)
run sudo pkill -STOP -l spindump; sudo pkill -STOP -l tailspind (you will be asked for your password once)

This will pause any running spindump processes (which is better than outright killing them because then they will be most likely restarted immediately).
Two caveats here

This will only work if the user you are logged in with has admin rights. If it doesn't, please add a comment and I can show you how to make this work for a non-admin user
It helps to put this in a shell alias (less character to type to execute it). If you need help with that, comment accordingly as well