The primary reason for the release of 7.0.9 was to address specific vulnerabilities and stability issues found in earlier 7.0.x versions.
Always consult the Fortinet Upgrade Path Tool to see if you can jump directly to 7.0.9 or if you need an intermediate "hop." fortigate 7.0.9
Version 7.0.9 introduced several hardware-level enhancements aimed at maximizing throughput: The primary reason for the release of 7