Subscription communications cab be paused by setting the DisableSubscriptions property to true for each driver instance. The purpose of the driver instance for each form is to have the granularity of pausing groups of subscriptions, so when the form is hidden that group of communications are paused. If a single instance were to be used for everything, then everything would update including hidden forms, therefore making update rates much slower.
To pause communcations, it would be like this:
EthernetIPforMicro800Com1.DisableSubscriptions = True