RAM is a primary memory and its contents are deleted after power is off.
Nowadays Minimum 8GB RAM systems are popular.
System Performance depends on various factors such as CPU and its generation, how much RAM is installed , size of cache memory and type of hard disk also add to the important factor.
If an SSD hard disk is used, OS performance will boost around 10 times compared to SATA hard disk in the computer.
Network performance will be depending on the Lan speed we are using in the network like 100Mbps or 1000Mbps.