Speed up laptop by virtual machine on OMV

My wife has an old Acer Aspire One 751h. WIth its Intel Atom processor it is not really powerfull and does not really benefit of 2GB of Ram. To not giving it to waste, I was thinking of running the OS in a virtual machine (VitualBox) on my HP ProLiant Microserver and connecting to it via WLan.

So I was looking for a tutorial to do so, but I was not able to find one suitable for me. So here my requirements:
- running Win7 in a VM on the Server (therefore i can find tutorials)
- at best a VNC-Only operating system to only connect to the VM needing as few CPU-power as possible.

The main purpose of this laptop is surfing. But running FIrefox or Chrome with more than 10 Tabs (online shopping) the laptop slows down and sometimes is not reacting for 30 seconds. I hope that with this setup I could make surfing more comfortable.

I am thankful for any information, tutorial or tips on how to improve the usability of the laptop.

Does nobody have an idea how to realize this?

Application virtualisation is not a really new topic (Sandboxing etc). Is there no possibility to outsource it to an server? I think these Citrix-Client/Server-System is offering a similar service. Has anybody tried Citrix in a VM or align with Openmediavault?

Last chance to help me Otherwise I have to accept that there will be no way