ok we currently have
2 vCores
1GB RAM
25ggb SSD storage
These are really minimal specs - you can obtain these specs with shared hosting plans for about £10/month without the overhead of running your operating system, Plesk, etc.
So, it's not surprising your website isn't loading quickly.
However before you look at throwing more resources at your website, I would look into these options:
- Upgrade to PHP 7 if you haven't already
- Ensure PHP's opcache is enabled
- Use page caching where possible
These improvements will help massively and compliment any resource upgrades.
I am looking at several options tonight - Baring in mind going forward we will anticipate having around 10,000 visitors daily with perhaps 50 concurrent users at any 1 time.
would 8gb be overkill in your opinion? or would 4gb be ok?
The important thing here is how you define "50 concurrent users", I am guessing you mean 50 people browsing the website at one time, which in reality might perhaps mean 10 concurrent page hits (PHP requests) per second.
To work out how much memory you need to serve this many users, you need to know how much memory each request uses on average - this varies between different websites. Let's say each request uses 50MB of memory while being processed, which is a typical amount, therefore for 10 concurrent page requests you would need 500MB memory. Then you need memory for MySQL - this would depend on the size and storage engine of your database so it's impossible to say, but let's call it 1GB - this should be plenty from what we know about your website so far. Then finally leave some overhead for the operating system and spikes, you might want a total of 2GB RAM bare minimum to run the website.
In terms of CPU, for a low number of concurrent requests, 1 modern CPU thread should realistically be enough.
I would therefore say, at a guess, that 4GB RAM would be absolutely fine for your website, even if the server is running a bloaty control panel too.
To give an idea I run a website handling 1,000,000 PHP requests per day (about 12/seconds on average, more at peak time) and a current average of 403 database queries per second (write heavy) on a standard 8GB (4 vCPU) DigitalOcean droplet with plenty of room for growth.
What's your budget for the new server?