When I have to wait longer than expected for a website to load, I don't use it as often. Subconsciously, I start avoiding the website all together, training myself to come up with workflows that don't involve it.
In a consumer setting, users leave when this happens. But in an enterprise setting where employees don't decide which software to use, employees are stuck. While this inertia is beneficial to stagnant vendors, employees suffer and become increasingly frustrated and less productive. If employers aren't adamant about keeping latency low, employees will start to devise their own work-arounds, which defeat the purpose of having centralized information repositories.
If you're unhappy waiting for pages to load, say something to your vendor. It's a fixable problem. Employees are often a company's most expensive resource. Make sure they have the tools they need to succeed.