You can increase the speed of OpenVPN connections by increasing the size of buffers in the config.
So, briefly, the buffer size is a value that indicates the maximum amount of data that will be transmitted per unit of time. It so happened that in OpenVPN this parameter is 64KB. At the same time, the number of sent packets per unit of time is limited by the rate of passage of these same packets. Accordingly, the lower we have the packet passing speed (the more ping will be), the lower the speed of OpenVPN we will receive.
Close the antivirus or firewall , Sometimes, antivirus or firewall is another burden on VPN speed, because it takes time to check the connection data for protection. The best solution is to close the antivirus and firewall program temporarily , but i recommend that you do not keep your Internet connection for long without activating these protection tools because there are many threats on the Internet .