Any tweaking techniques for virtual box VM you have in mind?
THE GOLDEN RULE:
Use Linux, not Windows - for all servers
That's the best speed improvement you will ever, ever achieve. All other recommendations are secondary
One thing to keep in mind is that a good VM needs a great computer, and a great VM needs an even better computer.
You can take this logic and apply it to RAM - If your computer has 16GB of RAM, you should probably limit your VM to 4GB or less, and if your computer has 8GB of RAM then give your VM 2GB. This is a general rule and not precise - but basically if your VM has too much memory or even an equal amount, there are times where your normal computer can't properly run anything because it isn't able to access enough resources. On the other side if your VM has too little memory your computer will function fine but your VM might not have enough to do anything.
Remember - 4GB of RAM is hardly anything. Most modern day computers are running 8GB as the new minimum for a lot of software and games, with 16GB being the recommended amount. I have 16GB of RAM on this laptop with an i7 processor, but even this will be outdated in another 4-6 years. Computers are always changing and hardware requirements are always going up.
You can try reducing the disk space given to the VM because sometimes a large VM, even when not fully used can get slow and buggy when it's given too many resources. This is especially true with older VM systems, older hardware, etc.
You said you're on windows, so you can try defragging your HD - if you haven't done this in a while, you definitely should.
You can try pausing or fully stopping anti-virus, file scanners, and other "in the background" software that hogs resources.
I also recommend upgrading your hard drive to SSD if you are using an older disk drive. SSD loads up in the blink of an eye and can run a LOT faster.