Many enterprises are running into network performance issues when they deploy Microsoft Office 365, according to research released Thursday by Zscaler.

The Challenges and Opportunities in Enterprise Office 365 Deployments report shows that 70 percent of enterprises deploying the leading SaaS productivity suite report latency issues on a weekly basis, 33 percent on a daily basis, and 69 percent report weekly bandwidth issues even after network upgrades, as existing infrastructures like firewalls and proxies can be overwhelmed by the persistent connections of Office 365.

Zscaler says 78 percent of IT decision makers use or plan to use Office 365, up from 64 percent in 2014. TechValidate surveyed 205 North American enterprise customers of Office 365 on behalf of Zscaler to understand how they prepared their networks for deployments, and what they had learned from their experiences.

According to the survey, 64 percent are concerned about bandwidth and latency before deploying Office 365, and C-level executives are 31 percent more likely than other staff to anticipate latency issues.

Over half of those surveyed (57 percent) said that their network favors personal and entertainment traffic over Office 365, and nearly half said that the cost of upgrades to support Office 365 exceeded their estimates.

Zscaler recommends that enterprises architect their network to allow direct access to the Microsoft cloud from branch offices. Only 33 percent of respondents had done so prior to deployment, but 70 percent are considering implementing direct internet connections, as well as traffic shaping and intelligent bandwidth allocation post-deployment.

“A fast and reliable Office 365 experience is key to a successful deployment,” the report authors write. “However, most organizations backhaul Office 365 traffic over a traditional hub and spoke network architecture that was never designed to support a fast user experience for modern cloud applications.”

Other recommendations include making sure that the enterprise firewall can scale, utilizing bandwidth control to prioritize Office 365 traffic, and maintaining centralized security control and automation as traffic is broken out locally.

Microsoft announced new measures to expand the Office 365 ecosystem with offerings from developers and ISVs at its Build 2017 conference earlier this month.