"Only" 91,000 rows... Why is this query even happening??

Forum #14 happens to be my (dreaded!) "Word Games" forum where idiots post nonsense over and over to build their post counts (hence I cannot wait for 7.3 so all that doesn't count any more!)...

And most importantly... could this be causing the server lag I've been experiencing?

GangsterBB.NET (Ver. 7.6.1.1)
PHP Version 5.6.40 / MySQL 5.7.23-23 (was 5.6.41-84.1) / Apache 2.4.54
2007 Content Rulez Contest - Hon Mention
UBB.classic 6.7.2 - RIP