About Fortigate 100D VPN Speed

Hi. I am using Fortigate 100D in Korea.

I do not have any problem with connection or speed when using VPN in Korea.

However, when I go to a foreign country (India, China, etc.) and connect to the VPN to connect to the company network, it takes a considerable time or stop to access the company server.

What do I need to check if this is the case?

The VPN connection is connected by sslvpn.