Thank you for contacting the Intel Communities.
The manufacturer of the device would be in charge of assigning how much VRAM is going to be available for you to use.
The reasoning behind why the other computer was able to run these games is because it had a dedicated graphics card, a component apart from the CPU that was in charge only of the graphics, which would allow it to have better performance while gaming since it is intended for that.
There different games that are playable with the Intel® HD Graphics, I invite you to check the link below, where you would be able to look for your CPU and see which games are supported by the Intel® HD Graphics inside your processor: Hardware Games
Regarding performance, it depends on the VRAM available to be used as well as the CPU itself, in this case if more VRAM is available with a possible change in your config, chances are that performance could increase.
If you require any further information or support, do not hesitate to contact us back.