Translation of zentraler

For example, if I am working very early in the morning, let's say 06.00 (that would be 09.00 your time), I don't notice it much. But 9 hours later, the system slows down, because people in Europe get online.
Therefore we use only the Vocabulix dictionary in our class. It has good features and a large vocabulary base. I will have to send you a few sentences for rewriting if that is OK with you, because the whole is mixed up.
Many thanks for your suggestions. They are very useful. I can't answer your mail now, but I will come back to you later when I'll have more time. I hope that you and your family are well!