Question Memory Upgrade best bang for buck for VM performance?

Nov 27, 2018
To start I want to give the current set up I'm working with. Yes I know there were some corners cut in a couple areas, because I built my workstation on a tighter budget than I'm currently on now.
Motherboard : Gigabyte B360M DS3H
CPU: i3-8100 4 cores 4 threads
GPU: Asus Dual GeForce GTX1060 3GB
RAM: Patriot Viper Elite Series DDR4 2x4GB 2400MHz
Drives: OS (C Drive) - Kingston SSD 120GB
B Drive: Samsung SSD 500GB
D Drive: Samsung T5 portable SSD 250GB

I always store my VMs on either my D drive or E drive. No I'm not a noob, all of my settings for my virtual machines and for VMware are tweaked as they should be. I understand my current physical RAM is a bit outdated. Which is why I have already ordered 2 more 4GB sticks, and they'll be installed in the next few days. My question is will this provide the best performance upgrade for my VMs for the money, or should I look at bumping to a i5/i7 9th gen CPU as well? I typically use my VMs to practice my pen testing (and some scam baiting every now and then). I would like to be able to run 2 or 3 VMs at simultaneously. Let me know what you all think. Any advice is appreciated.