Fresh server, page slowly

[Zhenmue]

this:

CPU	Intel(R) Xeon(R) Gold 6150 CPU @ 4 X 2.70GHz
Memory	4 GB (Cached: 3.71 GB/ Used: 3.71 GB, Free: 1.16 GB)

tells me you are in a VPS.
a VPS with 4 cores from 2017, not so fast, and 4 GB of RAM.
considering you have 1 table with 5 million records, it means your website is not small.

Move to another VPS, hopefully one with no %steal, and fast CPU like amd 5950 or 7950, it would make a big difference on speed.
and if you can go for 8gb ram, 4gb is too little.

good luck

 

[LawsHosting]

tells me you are in a VPS.
a VPS with 4 cores from 2017, not so fast, and 4 GB of RAM.

Well, I had a big client (600+ hits a second) on a dedi with 32gig ram, 8 cores, optimised PHP & MySQL......... Still, Wordstress complained....... I gave up in the end.......

 

[Zhenmue]

Well, I had a big client (600+ hits a second) on a dedi with 32gig ram, 8 cores, optimised PHP & MySQL......... Still, Wordstress complained....... I gave up in the end.......

Wordpress is very CPU demanding, specially for the Single core Speed,