There may be several reasons why your server is performing poorly. Check your server resource usage: CPU, RAM, Disk space, Bandwidth usage. Resource shortage will definitely have a huge impact on your server's performance.
Check your network connection to the server. Network problem in between your ISP and your server may cause delays or connection interruptions. Perform a 5 minute MTR test from your device to the server's IP address while the problem is occurring. This test will help you determine which network point is causing the network problems.
WinMTR - https://comparite.ch/mtr
Check error logs on your server. If the software you installed on the server is performing slowly, check application configuration and look for any errors. Check the error logs of your software to find more information about potential problems. Also, please read your software documentation for troubleshooting and / or configuration advises.
However, if you believe the problem resides in our internal systems rather than the server itself, please submit a ticket to our Support and provide as much detailed information as possible.