What is reduced when using VLANs in a network?

Utilizing VLANs (Virtual Local Area Networks) in a network significantly helps in reducing network congestion. VLANs allow network administrators to segment a single physical network into multiple logical networks, enabling better traffic management. By grouping related devices into the same VLAN, broadcast traffic is limited to those devices, reducing the amount of unnecessary traffic that all devices on the network must process.

This strategic segmentation means that devices on one VLAN can communicate freely without affecting devices on another VLAN. As a result, the overall amount of broadcast traffic is minimized, leading to a more efficient use of bandwidth and a reduction in latency and collisions that can occur in traditional flat networks. Consequently, this reduction leads to improved network performance and efficiency.

In contrast, while VLANs may indirectly influence hardware costs, management time, and end-user performance, their primary and most direct impact is on network congestion, making it the most fitting answer.