Hello,
currenlty have a AMD Ryzen 9 7950x @ 4.5GHz (16 cores + HT) and 64 GB of ram. However, when I get about 250 users the site crawls and some users get an error 500 page. I have tried MySQL optimization and I use litespeed. I am sure it can get a bit better with better optimization but I need to have it up and running by Nov 1 and so I just want to get a big server for now or maybe a server for website and another for database.

I am looking for something with 40 cores and 128 GB Ram, I run DirectAdmin now but don't really care about the control panel because there will only be two sites on it.
Any recommendations? What can you say about NetShop-isp.com.cy dedicated servers? Are they reliable?

The system works great, and their MySQL servers work better than any we have tried to date.
So if you want an inexpensive and very functional site, NetShop Isp host is the way to go. Like their Netherlands dedicated servers.

Few hosting providers conduct backup more than once a day and few do it less often. Backups are essential to save your data. And also make sure that your databases are also being backed up not only your files. Ask the hosting provider about his backup policy.

Well, NetShop ISP infrastructure spans across Europe, Asia Pacific and the United States with 15 Data Centers and global connectivity carriers.
Also get full admin/root access with every dedicated hosting package and 24/7 on-site technical support.
Locations: Cyprus, Malta, UK, Netherlands, Brazil, Japan, US, Singapore, Hong Kong.

To compete in the market, most web hosting providers are already offering affordable website hosting plans.
One can right away find quality affordable website hosting plans or packages on the internet in just a matter of few minutes.

Try considering GTHost.com Paris servers. Try 1xE5-2695v4, 128GB, 2x960GB SSD, 500M Unmetered starting at $159.
All servers with IPMI on board, they have a gray IP for security, they can be accessed through the admin, a real IP will be allocated for the duration of the session, the client can use IPMI at any time for free.