How to improve TTFB on nginx server?

Question

I'm running VPS (nginx version 1.18.0 on Ubuntu) in Charlotte, NC (QEMU Virtual CPU version 2.5+ 2399.998 MHz, up to 3.2 Ghz in turbo; 2gb RAM) and TTFB of my Wordpress sites aren't great. It's around 200-300ms in America, a bit worse in Canada and Europe and way off Asia/Australia.

I talked to VPS support, they moved site to FastCGI (Nginx + PHP-FPM) and added some code to nginx.conf but it improved TTFB slightly. I also enabled HTTP/2 via ISP Manager.

Anyway, here's full configuration:

user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 768;
    multi_accept on;
}

http {

    ##
    # Basic Settings
    ##

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    ##
    # SSL Settings
    ##

    ssl_protocols TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
    ssl_prefer_server_ciphers on;

    ##
    # Logging Settings
    ##

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    ##
    # Gzip Settings
    ##

    # gzip on;

    # gzip_vary on;
    # gzip_proxied any;
    # gzip_comp_level 6;
    # gzip_buffers 16 8k;
    # gzip_http_version 1.1;
    # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

#Optimization
proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;
fastcgi_max_temp_file_size 0;
proxy_connect_timeout 300;
proxy_send_timeout 300;
proxy_read_timeout 300;
fastcgi_connect_timeout 500;
fastcgi_send_timeout 500;
fastcgi_read_timeout 500;
client_header_timeout 1m;
client_header_buffer_size 2k;
client_body_buffer_size 256k;
ssl_buffer_size 4k;
large_client_header_buffers 4 8k;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
    include /etc/nginx/vhosts/*/*.conf;
    client_max_body_size 1024m;
    server {
        server_name localhost;
    disable_symlinks if_not_owner;
    listen 80;
    listen [::]:80;
    include /etc/nginx/vhosts-includes/*.conf;
    location @fallback {
        error_log /dev/null crit;
        proxy_pass http://127.0.0.1:8080;
        proxy_redirect http://127.0.0.1:8080 /;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        access_log off ;
    }
    }
}

#Optimisation is what was added by VPS support.

I played with numbers a bit, but to no avail. What can you suggest?

Here's detailed TTFB (used tools.keycdn.com): click