Reduce speed

Hello
I have a problem
I am using the plugin “Product CSV Import Export (BASIC)”
I use the free version
The previous hosting, I could import my product number 300000
My previous hosting was shared and have 256 MB of RAM
plugin your very excellent working
I bought VPS
I’m going to import 3 million products on my website
When the work becomes slower import any moment
Every moment becomes slower
Reduced speed at any moment
I asked VPS Hosting, said that there are no limits
I do not know what is the problem
I want to fix that
Just fix my problem. (problem = slow)
Specifications my VPS, SSD hard drive and 2 GB of RAM
Please help me
The sooner
Thankful