After the information you've provided it seems the cause is "Web Filtering". Typically an IT dept will use this to monitor and/or restrict which web sites can be accessed by users. This can add significant lag into a network/internet connection.

Please see the CLC technical Specifications document which lists the sites you'll need access to when attempting our courseware. It may be worth discussing with your IT dept to see if these sites can be "whitelisted" in order to speed up access to them.

There are two sets of servers users connect to when attempting a CLC learning module. The courseware is delivered to the user from the choota gateway (choota.com) and their progress is written to the database servers inside our network.
CLC Technical Specifications