Hi Matt, If you have a lot of events it can cause the pages in Mango to be sluggish. Several thousand should not cause this though so you might have a lot more.
You look at the logs so you know for sure but a solution would be to start the H2 web console and then manually purge your events table. See here for more help: https://help.infiniteautomation.com/support/solutions/articles/14000022661-about-the-h2-database
You can run
select count(*) from events
to see how many events total you have.
You can then run
delete from events
to delete all the events
Try starting Mango again. Once it starts up look at the events to see what is generating so many events and resolve. You can also go to the system setting page under Purge settings click the Delete all events button.
Let me know if that helps.