Extreme lag when opening folders, new tabs, dragging/minimizing any windows. and clicking on any text box
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