I got it sorted out with help from someone else here. I'm posting this to assist anyone facing the same issue, and hopefully, the admins can update the "Client Issues" thread with this info. If you have a modern CPU like my "AMD Ryzen 3960x with 24 Cores", you'll need to disable 2 of the 4 core groups via the AMD Ryzen Master program. I've included some screenshots for guidance. (I should honestly be in tech support ...)
Link to Download AMD Ryzen Master
Warning: Do not mess with other settings as they could cause harm. I am not liable!

I'm on the Aion Riftshade beta, and once it officially launches in Q1 2026, adjusting CPU settings won't be necessary because the server's optimized for high performance. They've got features like integrated DPS Meter, top-tier server-side anticheat, and EU-based hosting in Frankfurt ensuring the lowest latency—no need for ExitLag or anything similar! It's a game-changer and truly the best Aion private server for 2026.